heating and cooling research paper

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Heating and cooling research paper

Figure 7 shows a schematic diagram of the heat pump as a black box model for Winter Ground operating mode. The heat pump model receives the following inputs: the secondary fluid inlet temperature to the evaporator, T e i K brine in this case ; the secondary fluid temperature difference across the evaporator, dTe K ; the secondary fluid inlet temperature to the condenser, T c i K user loop in this case ; the compressor frequency, f comp Hz and the secondary fluid temperature difference across the condenser, dTc K.

Figure 8 shows the comparison between experimental measurements and the correlations results for the compressor consumption and the condenser capacity in Winter Ground operating mode M5. It can be observed that the adjustment is very accurate, being the maximum deviation lower than 3. Experimental measurements versus polynomial correlations for Winter-ground mode: a Compressor consumption.

Top graphs correspond to COP evaluated only with the compressor consumption whereas bottom graphs correspond to COP evaluated with all electric consumptions, i. The compressor frequency is 50 Hz. It should be noticed that the Y axis in Figure 9 shows an opposite trend to the Y axis in Figure 10 , since increasing the brine temperature difference across the evaporator in Figure 9 means decreasing the brine flow rate, whereas Y axis in Figure 10 shows the fan frequency, which is proportionally linked to the air flow rate.

As it can be observed in Figure 9 , the lower the temperature difference across the evaporator, the higher the compressor COP. In other words, the higher the brine flow rate, the higher the compressor COP. This trend is corrected when it is taken into account the brine circulation losses in the brine loop, since the pumping losses depend on the brine flow rate.

The result is that the optimum is situated around 3 K of temperature difference. Interestingly, this is the standard value employed by most of the manufacturers for this parameter, moreover, it is the one employed in the certification testing standards. In contrast, the maps show that the higher the water temperature difference through the condenser, the higher the COP, although the influence is lower than at the evaporator. This means that the lower the user flow rate, the higher is the COP.

Low flow rates imply a higher thermal resistance at the condenser so it should contribute to increase the condensing pressure and so to a COP decrease, which is not observed. This is because the mapping has been built with experimental results in which we keep constant the supply water temperature, which is the usual way of control of these kind of heat pumps. This makes that, in fact, when the condenser flow rate decreases, the temperature difference increases so that the user return temperature decreases, allowing a decrease in the condensing temperature that makes the COP increase.

Similar trends can be found in Figure 10 : the higher the water temperature difference through the condenser dTc , the higher the COP, although the influence is again lower than the one of the fan frequency at the evaporator. Again, the lower the user flow rate, the higher is the COP. In this case, it is much apparent the influence of the fan consumption on the global COP. If the pumps and fan consumptions are not taken into account, the higher the fan frequency, the higher the COP compressor because the thermal resistance at the evaporator decreases and therefore the evaporation temperature increases.

However, if the fan consumption is taken into account in the COP global , then, as the fan consumption increases with the fan speed, it reverses the influence and makes that the lower the fan frequency, the higher the global COP. After analysing Figures 9 and 10 , it can be concluded that the influence of the operating parameters on the system performance is very important. Therefore, the minimization of the energy consumption of these complex systems requires the optimization of its operation.

The model described in the following is a tool to assist the optimization of the sizing and operation of these type of systems. The layout of the system model is shown in Figure The heat pump is able to provide heating and cooling to the user, but also DHW.

In order to combine the different working modes, it is set that the heat pump will be able to provide DHW during the night from to On the other hand, it will only provide heating or cooling during the opening schedule of the building from to This means that the DHW tank has a high inertia, and only a small part of the hot water will be extracted during the day, so the heat pump will work in DHW mode only during short periods in the night.

On the user side, the maximum heating load during the year is around 12 kW and the maximum cooling load is around 6 kW. Regarding the circulation pumps, the user loop circulation pump is continuously working during the office schedule from to , while the ground loop and DHW loop circulation pumps cycle with the compressor operation they only work when the compressor is working.

The main innovations consist of an insulated inner pipe that reduces the heat transfer between the inner and outer pipe, together with a ribbed outer channel, which makes the fluid follow a spiral path along the outer pipe. According to preliminary investigations, it is possible to obtain a significant increase on the efficiency when compared to conventional BHEs, especially at low Reynolds numbers [ 12 ].

A model of this new coaxial-spiral BHE was developed based on the thermal network approach, combined with a vertical discretization. This model has been adapted to the new configuration from the B2G dynamic model previously developed for a U-tube BHE configuration and presented in Refs. A detailed explanation of the model can be found in Ref. As a preliminary control strategy, it was selected a simple strategy, in which the source with the most favourable temperature highest temperature in heating mode and lowest temperature in winter mode is selected.

In order to prevent the heat pump from changing from one source to another in a short period as the air temperature changes with a high frequency , a differential controller is used, providing some hysteresis to the control. This means that, the actual ground temperature is used as the reference temperature, and the heat pump changes the source to air when the air temperature is more favourable considering the dead band of the differential controller.

Figure 12 shows the operation of this control for a heating mode and b cooling mode. Selection of the source depending on the air and ground temperature. In order to programme this control easily in a control board, it is planned to use the fluid return temperature from the ground loop instead of the ground temperature, as it is easier to measure the temperature of the fluid inside the pipe rather than measuring the surrounding ground temperature.

In order to study the techno-economical feasibility of the DSHP system, two scenarios were compared. The aim of this comparison is to analyse whether it is possible to obtain a similar efficiency of the system but considering half the length of BHEs, which would mean a significantly reduced investment cost for the DSHP installation compared to that of a GSHP system.

The main design and operation parameters of the system considered in the model are shown in Table 2. Table 2. Parameters of the system. The building that has been used in this analysis is a small office building located in the city of Amsterdam, The Netherlands. This building has two zones with necessities of heating and cooling: an office room and a meeting room.

The thermal demand loads have been calculated using a TRNSYS model of this building and then, introduced in the global model of the system as an input. It is assumed that in the building there are three people working in average. The model considers the different walls of the building and windows, as well as the materials, infiltrations and ventilation required in the building.

So, the sensible and latent gains that are needed to meet the comfort inside the different rooms are calculated based on the external conditions outdoor temperature, radiation on the different facades and humidity , the internal conditions indoor temperature, humidity and the overall heat transfer coefficient calculated from the building envelope characteristics.

The maximum peak loads are around Thermal demand load profile. In this profile, the demand litres per hour is given for each hour of the day. Figure 14 represents this DHW demand profile during one day. This means that the investment of the installation will be significantly reduced, as the BHE field is one of the most expensive parts in a GSHP system. In the first scenario, a GSHP system is analysed. The efficiency of each system is assessed by calculating the SPFs.

Figure 15 presents the results for the assessment of the systems energy performance over a whole year of operation. Seasonal performance factors for a whole year of operation in the two scenarios: a ground source heat pump system first scenario and b dual source heat pump system second scenario.

So, it can be concluded that both systems are able to work with a similar efficiency, this means that they can provide the same amount of energy to the system with the same power consumption. Then, as the system is mainly operating in heating mode during most part of the year shown in Figure 16 , the yearly value of SPF 1 is 3.

In general, it can be concluded that the SPFs obtained during the summer are quite higher than the ones obtained during the winter due to the use of free-cooling and natural ventilation. This happens because during the operation in these modes, the heat pump is switched off and there is no consumption of the compressor, only the consumption of the ground and user loops circulation pumps in the case of the free-cooling and the parasitic losses of the heat pump in both modes.

Figure 16 shows the amount of time in which the DSHP works in each mode. It is possible to check that most of the year it is working in heating mode mostly using the ground as a source. During the summer, the heat pump works just a few hours in cooling mode, being the free-cooling mode the most used as expected. The rest of the cooling demand is met by natural ventilation and the inertia of the building midseason mode. This section presents a preliminary analysis of the system energy performance during 1 week of operation in order to describe the dynamic behaviour of the dual source system and the selection of working mode for 1 typical week in heating mode.

Figure 17 shows the selection of working mode during 1 typical week in autumn. It is possible to see that, as the air and ground temperature change, the heat pump will select one source or the other, selecting the most favourable, as it was already explained in Section 3. When the air temperature is higher than the ground temperature, the heat pump will select the air as source in heating mode as well as in DHW mode.

Analogously, when the air temperature becomes lower than the ground temperature considering the hysteresis in the control , the source will change from air to ground. On the other hand, if the air temperature is lower than the ground temperature and then, the air temperature becomes higher, the source will change from ground to air.

Figure 18 presents the percentage of time during which the system has been working in each operation mode over the year. In the case that the air is hotter than Working mode time ratio for 1 year of operation of the dual source system: a Winter season and b Summer season. This percentage is much lower than that of the heating mode operation, mainly due to the low DHW demand, which is practically zero during the night.

On the other hand, as the system will be working in heating mode extracting heat from the ground during most part of the year, special attention should be paid to the summer where the heat injected into the ground is very low. This could let the ground thermally recover during the summer, but it may not be enough in order to reach a thermal balance in the ground, making it necessary to inject heat in the ground during the summer. This highlights the need for developing energy optimization and control operation strategies to avoid this situation and make the system work under its optimal operation point.

By using the TRNSYS model developed in this research work, it will be possible to analyse the energy performance of the system and its impact in the ground temperature evolution over the years. Therefore, the model developed can be an assisting tool for the optimal design and operation of the system and also to assess the system energy performance and its suitability for other European countries with higher cooling thermal loads and lower heating thermal loads than the analysed case.

For instance, a previous research work was carried out by the authors in Ref. It was concluded that this type of DSHP system is even more convenient for Mediterranean climates mostly cooling dominated , not only leading to a reduction in the size of the ground source heat exchanger needed, but also presenting a higher yearly SPF SPF 4 equal to 4. This is mainly due to the higher efficiency of the DSHP prototype in cooling mode than in heating mode.

Therefore, it can be concluded that the greater the cooling thermal demand of the location, the higher the annual SPF 4. The heat pump is able to employ either the air or the brine coming from the ground as heat sources in winter and provide hot water for heating the building. The unit is reversible, so it can also provide cooling during summer using the air or brine as a sink. Besides, it provides DHW all along the year, and in summer conditions, it can use the condensing waste heat to produce DHW.

The heat pump is an outdoor unit, very similar to an air—water heat pump unit. The unit has turned to be fully reliable with a smooth simple and full automatic operation. The DSHP works with R32 refrigerant and includes a variable speed compressor which give full capabilities for an efficient modulating operation.

The unit has been fully tested at the laboratory with very accurate instrumentation and this has allowed the characterization of its performance with simple polynomials. The article includes a brief summary of its performance, including a small study about the influence of some important operating parameters on the system performance. In order to assess the energy performance of the heat pump during 1 year of operation, an integrated system model has been developed in TRNSYS.

The assessment consisted of two different steps. Then, the second step consisted of an analysis of the DSHP system operation and energy performance along 1 year. The system presented a yearly performance factor SPF 4 around 3. It was concluded the need for developing key control strategies to optimize the seasonal energy performance of this type of system.

Comparison between the energy performance of a ground coupled water to water heat pump system and an air to water heat pump system for heating and cooling in typical conditions of the European Mediterranean coast. Energy Convers Manage ; 49 : — Google Scholar. Energy analysis of a solar-ground source heat pump system with vertical closed-loop for heating applications. Energy ; 36 : — Lazzarin RM. Dual source heat pump systems: operation and performance. Energy Build ; 52 : 77 — Energy Build ; 93 : — Optimization of hybrid—ground coupled and air source—heat pump systems in combination with thermal storage.

Appl Therm Eng ; 30 : — 7. Development of dual-source hybrid heat pump system using groundwater and air. Energy Build ; 42 : — Corberan JM. New trends and developments in gound-source heat pumps. In Rees SJ ed. Woodhead Publishing , : — Google Preview.

Hybrid ground source heat pump systems. Modelling and energy analysis of a dual source heat pump system in an office building. Witte H. Innostock Experimental validation of a short-term Borehole-to-Ground B2G dynamic model. Appl Energy ; : — Energy Convers Manage ; : — Modelling and experimental validation of a novel co-axial spiral borehole heat exchanger. Chapter Service Water Heating , Development and experimental validation of a TRNSYS dynamic tool for design and energy optimization of ground source heat pump systems.

Energies ; 10 : Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide. Sign In or Create an Account. Sign In. Advanced Search. Search Menu. Skip Nav Destination Article Navigation.

Close mobile search navigation Article Navigation. Volume Article Contents Abstract. Article Navigation. Oxford Academic. Corresponding author: ancamar4 upvnet. Javier Marchante-Avellaneda. Carla Montagud. Select Format Select format. Permissions Icon Permissions. Abstract This article presents the characteristics and performance of an innovative dual source heat pump DSHP for heating, cooling and domestic hot water DHW production. Figure 1. Open in new tab Download slide.

Basic structure and components of the dual source heat pump. Operating mode. Open in new tab. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Black box model for the heat pump in Winter Ground mode. According to the major factors, orthogonal array L25 is engaged for Taguchi experiments. Based on L25 of Taguchi experiments, the best successful result is analysed to select the level of major factors.

The result of Taguchi optimisation was introduced into Comsol Multiphysics software and EM was performed using the determined critical points again. The experimental results show the successful location for cooling and heating appliances compared to the initial design of room 1. Cooling options for high-average-power laser mirrors. This deformation is caused by the thermal stress arisen due to parasitic absorption of 1 kW square-shaped flat-top laser This deformation is caused by the thermal stress arisen due to parasitic absorption of 1 kW square-shaped flat-top laser beam in the dielectric multi-layer structure.

Deformation depends on amount of absorbed power and geometry of the mirror as well as on the heat removal scheme. The absorbed power has been considered to be much higher than that expected in reality to assess the worst case scenario. Rectangular and circular mirrors made of zerodur low thermal expansion glass were considered for these simulations. The effect of coating layers on induced deformations has been neglected. Induced deformation of the mirror surface can significantly degrade the quality of the laser beam in the beam delivery system.

Therefore, the proper design of the cooling scheme for the mirror in order to minimize the deformations is needed. Three possible cooling schemes of the mirror have been investigated. The first one takes advantage of a radiation cooling of the mirror and a copper heatsink fixed to the rear face of the mirror, the second scheme is based on additional heat conduction provided by flexible copper wires connected to the mirror holder, and the last scheme combines two above mentioned methods.

Furnace Repair Cleveland Ohio. Man has become very advanced now a day. This advancement has brought a lot of changes in his life. These changes can be good or bad in some ways. Man has been dependent on machines for his every work. He has become more and more busy. In the past, people were used to do all their works with their own hands and this kept them active and energetic.

Activeness is very important for a healthy life. When the people had done their work by their own hands, they all were healthy and strong. The life in the past was not so much fast. The people were used to meet with one another and shared their all the happiness and sorrows with one another. But now life has become very fast and dependent. People depend on the machines for their all types of works.

This has good as well as bad aspects. All the people have been very lazy and idol. They can't do any work without machines. Harmful radiations are released from the electronic devices. These harmful rays can create a lot of health problem. The good aspect of these machines to do their work, he can save his time and energy because the machines can do work faster than human beings. Conserv Air is a brand which can provide you the services of best heating and cooling systems.

We can install the cooling and heating systems and also can repair them. In different areas, weather comes with intense conditions. In these areas, your heating and cooling systems. A heating system for a specific climate. Experiences with Temperierung in the city of Cremona. Nowadays, considering the importance of the energy issue, it has become a major concern of economic topic.

According to the energy balance sheet data, more than one third of the total energy consumption in Iran is consumed in the building According to the energy balance sheet data, more than one third of the total energy consumption in Iran is consumed in the building sector. With regard to the massive waste of energy in the existing buildings, as well as the low efficiency of heating and cooling systems, seeking the right solution to reduce energy consumption in this sector is of utmost important.

In this study, based on mathematical modeling, a solution has been presented to help us choose a proper combination of primary building materials and active or inactive air conditioning systems for residential buildings. It aimed to minimize both costs and thermal energy consumption of building materials. The proposed model has been utilized for a residential building in Tehran. Then, the optimal combinations of materials have been determined based on national building regulations code As the ice cold can beads up with moisture you are left longing for a refreshing cold drink.

However it is less refreshing to be reminded that cold surfaces in our homes However it is less refreshing to be reminded that cold surfaces in our homes can bead up with condensation just like the soda can in the commercial. The cold surfaces in our home are prone to condensation too. Fine in the commercial, but unfortunately not so good in your home.

In some climates mold can be hard to prevent. We explore ways you can avoid conditions that promote mold growth. Remote inspection of underground heat supplying systems on the basis of aerial infrared thermography AIT is able to find latent leaks of hot water and other imperfections malfunctions. Moreover, AIT data allow forecasting the places Moreover, AIT data allow forecasting the places of future leaks and efficiently choosing the zones of heating lines for high-prior reconstruction, according to their actual technical condition, rather than their age.

Long-term changes of meteorological conditions of urban heat island development in the region of Debrecen, Hungary. Meteorological conditions have a remarkable impact on urban climate similarly to other local and microscale climates. Clear skies and calm weather are advantageous for the development of the urban heat island UHI. There are numerous There are numerous studies on the spatial and temporal features of the phenomenon.

Much less attention is paid, however, to the meteorological conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies of advantageous and disadvantageous meteorological conditions for UHI development on the basis of a year-long time series. Meteorological condition categories of UHI development have been established on the basis of wind speed values, cloudiness, and precipitation ranging from advantageous to disadvantageous conditions.

Frequencies of occurrence of condition categories of UHI development were determined first. Advantageous and moderately advantageous conditions were found to be dominant in the time series. Linear trend analysis revealed a significant increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous conditions was analyzed for the years, seasons, and months of the study period as well.

Spring and summer April and June produced significant increasing trends of frequencies of advantageous conditions, while winter with the exception of February and autumn did not show significant increase of those frequencies. Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter significantly. Boosting renewable energy in heating and cooling.

Fact sheet for six case studies. Client: European Commission Horizon This report sums up the results of the analysis of barriers and drivers to the deployment of heating and cooling solutions based on renewable energy sources RES , carried out in the framework of the progRESsHEAT project Work Package 3. Based on the review of existing policies task 3. Analysis of heat transfer inside wall-joint-fins systems. Heat transfer inside wall-joint-fins systems is analyzed.

The coupled two-dimensional energy equations of the wall and the joint-fin are solved numerically using an iterative high order scheme finite volume method. Advanced fine Advanced fine analytical solution is proposed and various closed form equations for different heat transfer augmentation indicators are obtained. Excellent agreement is noticed between the numerical and the analytical results. Wall-joint-fins systems are more effective in transferring thermal energy when the joint-fin is made of a highly conductive material.

Moreover, varying the joint-fin lengths ratio may increase the system effectiveness by a factor of 1. The maximum system effectiveness which occurs at specific geometrical aspect factors increases as convective heat transfer coefficients increase. Furthermore, the effectiveness and efficiency of the wall-joint-fins system increase as the relative joint-fins to wall volume ratio increases.

The wall-joint-fins efficiency is least affected by the joint-fin lengths ratio. Eventually, the heat transfer coefficient between the joint-fin and the wall is identified. Finally, wall-joint-fin systems are recommended as heat transfer enhancing elements. Numerical and analytical studies are carried out to investigate natural convection in an inclined porous cavity filled with a volumetric heat source. Heat fluxes are imposed on the sidewalls to ensure a cooling process.

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Scroll technology has been chosen because its superior efficiency at these operating conditions. The optimum compressor size would be the smallest possible one that could provide the demand in the worst conditions running at maximum speed. In this way, it would be able to cope with the peak demand but still have a good system performance for most of the time in part load and a wide modulation capacity.

However, the commercial availability of compressors for the chosen refrigerant R32 was very small at the moment of designing the heat pump. Among the available compressors, it was chosen the smallest variable speed compressor available for R As explained above, the adopted DSHP concept is based on an air to water heat pump.

The frame dimensions of the heat pump prototype were selected in order to have space enough to fit all the necessary components. On the other side of the coil the fans were situated. The RTPF consisted of two rows of tubes of 8 mm diameter, with five refrigerant circuits. Asymmetric plate models by SWEP have been selected in order to minimize the refrigerant charge and reduce the pressure drop on the water loops. As the unit has a large number of different operation modes and the evaporator changes from one heat exchanger to another, the control of the superheat is metered at the compressor suction, which is common for all operation modes.

For the same reason there is no way to implement pressure compensation. Anyhow, the pressure drop through the different evaporators has been estimated to be low. Additionally, the control system measures the discharge temperature and if this temperature increases over a certain threshold it controls the EEV in a way that some pulses of liquid refrigerant are sent to the compressor suction in order to cool down the compressor. The selection of the adequate diameters for the pipes of the different lines of the unit has been based first on two main targets: first, avoiding excessive pressure losses; and second, insuring a minimum velocity in order to get the return of the oil at low compressor velocities.

This is especially critical for the suction line. For those pieces of pipe that change their role from one mode to another, for instance, from part of the liquid line to part of an expansion line, the most critical criteria has been selected in order to satisfy the design conditions.

The three required circulation pumps are also included in the frame of the heat pump: ground pump, user pump and DHW pump. A modelling study was performed by means of IMST-ART [ 11 ] in order assist the design of the heat pump, for each of the different operating modes. Besides, it has provided an initial estimation of the heat pump performance.

Figure 2 shows the basic layout and composition of the heat pump in its frame. As it can be seen, the air coil is situated in the front, and the fans in the back panel. The three BPHEs, the compressor, the liquid receiver and the three circulation pumps are visible in the picture.

It should be pointed out the clean layout of the heat pump and the compactness of the unit. A first set of 29 steady test points were performed, including the most important operation modes and conditions, which was employed to analyse the unit performance and prepare the general testing campaign. These tests allowed to check the adequate refrigerant charge and check the effective oil return and have a first estimation of the unit performance.

Additionally, with these results, the compressor efficiencies were evaluated and it was found a slight decrease of efficiency from the estimated values obtained from the RA results supplied by the compressor manufacturer. The compressor efficiency correlations were conveniently readjusted to the experimental data and they were introduced in the IMST-ART software. Then a comparison between predicted and measured results was performed for all the available test points. A very good agreement was found between the predicted and the measured results, so it was decided to employ the software to explore the variability of the unit performance when the input variables were changed, covering the whole range of possible variation for them.

For instance, for winter-ground mode, the input variables are inlet brine temperature to the evaporator, brine flow rate or brine temperature variation across the evaporator , inlet water temperature to the user condenser, user loop mass flow rate or water temperature variation across the condenser and compressor frequency.

For air source modes, the brine temperature and the brine flow rate, are not employed and instead, the input variables are the outdoor air temperature and the air flow rate or the fan frequency. IMST-ART was employed to evaluate the unit performance in the whole range of variation for Winter-ground heating mode, totalling test runs. The performance results, mainly condenser capacity, evaporator capacity and compressor consumption for all points, were employed in order to find a convenient polynomial, containing linear and quadratic terms, and also some crossed variables terms.

The study was performed employing the fitting by linear regression. The study was carried out manually by inserting new terms and retaining those that have obtained good estimation indicators until no further significant improvement was reached in the adjusted R 2 and the maximum relative error. Several DOE methodologies were tried and tested, in order to find which one was able to give the best compromise between the number of test points and accuracy in the determination of the corresponding RS.

The best compromise was found with the Central Compact Design methodology and it turned out that selecting only one of the two orthogonal blocks and central star it was sufficient to get a very good estimation of the RS all over the entire domain of the five independent variables, resulting in only 30 test points.

Once the test matrices were elaborated for each operating mode, the test campaign was followed until all the necessary points were tested for all the seven operating modes. The test matrices were adequately corrected when the variation of some parameter could go beyond the testing capabilities or the test point was in an area of no interest for the targeted application, for instance when the unit will not be in operation because it is much more profitable to employ the free cooling system.

All test results were systematically analysed in order to detect possible operation problems or mistakes, and be able to repeat them if necessary. After all the test results became available, the compressor correlation was checked again and readjusted, and the performance for each test point was also evaluated with the software. This allowed a basis to analyse the results and to check the unit performance and the possible existence of testing mistakes. A comparison between experimental and predicted performance was carried out for each operating mode.

This comparison allowed to deeply analyse the results and check all the individual test points. A very good agreement between estimated and measured results was found all across the different test matrices for all the seven operating modes. Figure 3 shows the heating capacity, the compressor power input, and the COP calculated only taking into account the compressor consumption for Winter Ground operating mode.

As it can be observed, both the heating capacity and the compressor consumption increase with the compressor speed in a quite linear way. The maximum COP is obtained around 40 Hz for both applications, with a significant performance decay.

However, this is only due to the fact that the air temperature is much higher than the return brine temperature, so the performance between both working modes cannot be fairly compared. In any case, the high values of air operation at moderate temperatures 7 6 supports the concept of taking the heat from the air when the air temperature is high or mild, reserving the ground for the lowest ambient temperatures. Again, the maximum COP is obtained around 40 Hz of compressor speed.

Once the results for each operating mode became available, they were employed to fit the developed performance polynomials, which will be afterwards employed for the system models and for the optimization of the system control. These polynomial correlations were obtained from the experimental results for the condenser capacity, evaporator capacity and compressor power input, and allow a full characterization of the heat pump performance among all the operation modes and a large range of operating conditions.

An example of the employed polynomial correlations is presented in the following. The main reason for this instead of using the already available heat pump TRNSYS types was the need of accurately reproducing the heat pump performance under different working conditions, which depends not only on the source and load inlet temperature but also on many other variables, as previously stated, for each 1 of the 11 operation modes.

On the other hand, a disadvantage of the already available heat pump types in TRNSYS, is that they calculate the performance of the heat pump based on a fixed number of working points and interpolate the performance when operating under other different conditions. Furthermore, they calculate the heat rejected or absorbed in the source side ground or air as the sum if it is in cooling mode or the subtraction if it is in heating mode of the heat pump capacity and the power consumption, not considering the thermal losses in the heat pump cycle.

Contrary to this, the heat pump model based on the correlations calculates the condenser and evaporator capacity, the power consumption and parasitic losses separately, based on the experimental results. Figure 7 shows a schematic diagram of the heat pump as a black box model for Winter Ground operating mode. The heat pump model receives the following inputs: the secondary fluid inlet temperature to the evaporator, T e i K brine in this case ; the secondary fluid temperature difference across the evaporator, dTe K ; the secondary fluid inlet temperature to the condenser, T c i K user loop in this case ; the compressor frequency, f comp Hz and the secondary fluid temperature difference across the condenser, dTc K.

Figure 8 shows the comparison between experimental measurements and the correlations results for the compressor consumption and the condenser capacity in Winter Ground operating mode M5. It can be observed that the adjustment is very accurate, being the maximum deviation lower than 3. Experimental measurements versus polynomial correlations for Winter-ground mode: a Compressor consumption. Top graphs correspond to COP evaluated only with the compressor consumption whereas bottom graphs correspond to COP evaluated with all electric consumptions, i.

The compressor frequency is 50 Hz. It should be noticed that the Y axis in Figure 9 shows an opposite trend to the Y axis in Figure 10 , since increasing the brine temperature difference across the evaporator in Figure 9 means decreasing the brine flow rate, whereas Y axis in Figure 10 shows the fan frequency, which is proportionally linked to the air flow rate.

As it can be observed in Figure 9 , the lower the temperature difference across the evaporator, the higher the compressor COP. In other words, the higher the brine flow rate, the higher the compressor COP. This trend is corrected when it is taken into account the brine circulation losses in the brine loop, since the pumping losses depend on the brine flow rate.

The result is that the optimum is situated around 3 K of temperature difference. Interestingly, this is the standard value employed by most of the manufacturers for this parameter, moreover, it is the one employed in the certification testing standards. In contrast, the maps show that the higher the water temperature difference through the condenser, the higher the COP, although the influence is lower than at the evaporator. This means that the lower the user flow rate, the higher is the COP.

Low flow rates imply a higher thermal resistance at the condenser so it should contribute to increase the condensing pressure and so to a COP decrease, which is not observed. This is because the mapping has been built with experimental results in which we keep constant the supply water temperature, which is the usual way of control of these kind of heat pumps.

This makes that, in fact, when the condenser flow rate decreases, the temperature difference increases so that the user return temperature decreases, allowing a decrease in the condensing temperature that makes the COP increase. Similar trends can be found in Figure 10 : the higher the water temperature difference through the condenser dTc , the higher the COP, although the influence is again lower than the one of the fan frequency at the evaporator. Again, the lower the user flow rate, the higher is the COP.

In this case, it is much apparent the influence of the fan consumption on the global COP. If the pumps and fan consumptions are not taken into account, the higher the fan frequency, the higher the COP compressor because the thermal resistance at the evaporator decreases and therefore the evaporation temperature increases.

However, if the fan consumption is taken into account in the COP global , then, as the fan consumption increases with the fan speed, it reverses the influence and makes that the lower the fan frequency, the higher the global COP. After analysing Figures 9 and 10 , it can be concluded that the influence of the operating parameters on the system performance is very important. Therefore, the minimization of the energy consumption of these complex systems requires the optimization of its operation.

The model described in the following is a tool to assist the optimization of the sizing and operation of these type of systems. The layout of the system model is shown in Figure The heat pump is able to provide heating and cooling to the user, but also DHW.

In order to combine the different working modes, it is set that the heat pump will be able to provide DHW during the night from to On the other hand, it will only provide heating or cooling during the opening schedule of the building from to This means that the DHW tank has a high inertia, and only a small part of the hot water will be extracted during the day, so the heat pump will work in DHW mode only during short periods in the night.

On the user side, the maximum heating load during the year is around 12 kW and the maximum cooling load is around 6 kW. Regarding the circulation pumps, the user loop circulation pump is continuously working during the office schedule from to , while the ground loop and DHW loop circulation pumps cycle with the compressor operation they only work when the compressor is working.

The main innovations consist of an insulated inner pipe that reduces the heat transfer between the inner and outer pipe, together with a ribbed outer channel, which makes the fluid follow a spiral path along the outer pipe. According to preliminary investigations, it is possible to obtain a significant increase on the efficiency when compared to conventional BHEs, especially at low Reynolds numbers [ 12 ].

A model of this new coaxial-spiral BHE was developed based on the thermal network approach, combined with a vertical discretization. This model has been adapted to the new configuration from the B2G dynamic model previously developed for a U-tube BHE configuration and presented in Refs.

A detailed explanation of the model can be found in Ref. As a preliminary control strategy, it was selected a simple strategy, in which the source with the most favourable temperature highest temperature in heating mode and lowest temperature in winter mode is selected.

In order to prevent the heat pump from changing from one source to another in a short period as the air temperature changes with a high frequency , a differential controller is used, providing some hysteresis to the control. This means that, the actual ground temperature is used as the reference temperature, and the heat pump changes the source to air when the air temperature is more favourable considering the dead band of the differential controller.

Figure 12 shows the operation of this control for a heating mode and b cooling mode. Selection of the source depending on the air and ground temperature. In order to programme this control easily in a control board, it is planned to use the fluid return temperature from the ground loop instead of the ground temperature, as it is easier to measure the temperature of the fluid inside the pipe rather than measuring the surrounding ground temperature.

In order to study the techno-economical feasibility of the DSHP system, two scenarios were compared. The aim of this comparison is to analyse whether it is possible to obtain a similar efficiency of the system but considering half the length of BHEs, which would mean a significantly reduced investment cost for the DSHP installation compared to that of a GSHP system.

The main design and operation parameters of the system considered in the model are shown in Table 2. Table 2. Parameters of the system. The building that has been used in this analysis is a small office building located in the city of Amsterdam, The Netherlands. This building has two zones with necessities of heating and cooling: an office room and a meeting room. The thermal demand loads have been calculated using a TRNSYS model of this building and then, introduced in the global model of the system as an input.

It is assumed that in the building there are three people working in average. The model considers the different walls of the building and windows, as well as the materials, infiltrations and ventilation required in the building. So, the sensible and latent gains that are needed to meet the comfort inside the different rooms are calculated based on the external conditions outdoor temperature, radiation on the different facades and humidity , the internal conditions indoor temperature, humidity and the overall heat transfer coefficient calculated from the building envelope characteristics.

The maximum peak loads are around Thermal demand load profile. In this profile, the demand litres per hour is given for each hour of the day. Figure 14 represents this DHW demand profile during one day. This means that the investment of the installation will be significantly reduced, as the BHE field is one of the most expensive parts in a GSHP system.

In the first scenario, a GSHP system is analysed. The efficiency of each system is assessed by calculating the SPFs. Figure 15 presents the results for the assessment of the systems energy performance over a whole year of operation. Seasonal performance factors for a whole year of operation in the two scenarios: a ground source heat pump system first scenario and b dual source heat pump system second scenario.

So, it can be concluded that both systems are able to work with a similar efficiency, this means that they can provide the same amount of energy to the system with the same power consumption. Then, as the system is mainly operating in heating mode during most part of the year shown in Figure 16 , the yearly value of SPF 1 is 3.

In general, it can be concluded that the SPFs obtained during the summer are quite higher than the ones obtained during the winter due to the use of free-cooling and natural ventilation. This happens because during the operation in these modes, the heat pump is switched off and there is no consumption of the compressor, only the consumption of the ground and user loops circulation pumps in the case of the free-cooling and the parasitic losses of the heat pump in both modes.

Figure 16 shows the amount of time in which the DSHP works in each mode. It is possible to check that most of the year it is working in heating mode mostly using the ground as a source. During the summer, the heat pump works just a few hours in cooling mode, being the free-cooling mode the most used as expected. The rest of the cooling demand is met by natural ventilation and the inertia of the building midseason mode.

This section presents a preliminary analysis of the system energy performance during 1 week of operation in order to describe the dynamic behaviour of the dual source system and the selection of working mode for 1 typical week in heating mode. Figure 17 shows the selection of working mode during 1 typical week in autumn. It is possible to see that, as the air and ground temperature change, the heat pump will select one source or the other, selecting the most favourable, as it was already explained in Section 3.

When the air temperature is higher than the ground temperature, the heat pump will select the air as source in heating mode as well as in DHW mode. Analogously, when the air temperature becomes lower than the ground temperature considering the hysteresis in the control , the source will change from air to ground.

On the other hand, if the air temperature is lower than the ground temperature and then, the air temperature becomes higher, the source will change from ground to air. Figure 18 presents the percentage of time during which the system has been working in each operation mode over the year. In the case that the air is hotter than Working mode time ratio for 1 year of operation of the dual source system: a Winter season and b Summer season.

This percentage is much lower than that of the heating mode operation, mainly due to the low DHW demand, which is practically zero during the night. On the other hand, as the system will be working in heating mode extracting heat from the ground during most part of the year, special attention should be paid to the summer where the heat injected into the ground is very low.

This could let the ground thermally recover during the summer, but it may not be enough in order to reach a thermal balance in the ground, making it necessary to inject heat in the ground during the summer. This highlights the need for developing energy optimization and control operation strategies to avoid this situation and make the system work under its optimal operation point. By using the TRNSYS model developed in this research work, it will be possible to analyse the energy performance of the system and its impact in the ground temperature evolution over the years.

Therefore, the model developed can be an assisting tool for the optimal design and operation of the system and also to assess the system energy performance and its suitability for other European countries with higher cooling thermal loads and lower heating thermal loads than the analysed case.

For instance, a previous research work was carried out by the authors in Ref. It was concluded that this type of DSHP system is even more convenient for Mediterranean climates mostly cooling dominated , not only leading to a reduction in the size of the ground source heat exchanger needed, but also presenting a higher yearly SPF SPF 4 equal to 4. This is mainly due to the higher efficiency of the DSHP prototype in cooling mode than in heating mode.

Therefore, it can be concluded that the greater the cooling thermal demand of the location, the higher the annual SPF 4. The heat pump is able to employ either the air or the brine coming from the ground as heat sources in winter and provide hot water for heating the building. The unit is reversible, so it can also provide cooling during summer using the air or brine as a sink. Besides, it provides DHW all along the year, and in summer conditions, it can use the condensing waste heat to produce DHW.

The heat pump is an outdoor unit, very similar to an air—water heat pump unit. The unit has turned to be fully reliable with a smooth simple and full automatic operation. The DSHP works with R32 refrigerant and includes a variable speed compressor which give full capabilities for an efficient modulating operation.

The unit has been fully tested at the laboratory with very accurate instrumentation and this has allowed the characterization of its performance with simple polynomials. The article includes a brief summary of its performance, including a small study about the influence of some important operating parameters on the system performance.

In order to assess the energy performance of the heat pump during 1 year of operation, an integrated system model has been developed in TRNSYS. The assessment consisted of two different steps. Then, the second step consisted of an analysis of the DSHP system operation and energy performance along 1 year.

The system presented a yearly performance factor SPF 4 around 3. It was concluded the need for developing key control strategies to optimize the seasonal energy performance of this type of system. Man has become very advanced now a day. This advancement has brought a lot of changes in his life. These changes can be good or bad in some ways. Man has been dependent on machines for his every work. He has become more and more busy. In the past, people were used to do all their works with their own hands and this kept them active and energetic.

Activeness is very important for a healthy life. When the people had done their work by their own hands, they all were healthy and strong. The life in the past was not so much fast. The people were used to meet with one another and shared their all the happiness and sorrows with one another. But now life has become very fast and dependent.

People depend on the machines for their all types of works. This has good as well as bad aspects. All the people have been very lazy and idol. They can't do any work without machines. Harmful radiations are released from the electronic devices. These harmful rays can create a lot of health problem.

The good aspect of these machines to do their work, he can save his time and energy because the machines can do work faster than human beings. Conserv Air is a brand which can provide you the services of best heating and cooling systems. We can install the cooling and heating systems and also can repair them.

In different areas, weather comes with intense conditions. In these areas, your heating and cooling systems. A heating system for a specific climate. Experiences with Temperierung in the city of Cremona. Nowadays, considering the importance of the energy issue, it has become a major concern of economic topic.

According to the energy balance sheet data, more than one third of the total energy consumption in Iran is consumed in the building According to the energy balance sheet data, more than one third of the total energy consumption in Iran is consumed in the building sector. With regard to the massive waste of energy in the existing buildings, as well as the low efficiency of heating and cooling systems, seeking the right solution to reduce energy consumption in this sector is of utmost important.

In this study, based on mathematical modeling, a solution has been presented to help us choose a proper combination of primary building materials and active or inactive air conditioning systems for residential buildings. It aimed to minimize both costs and thermal energy consumption of building materials.

The proposed model has been utilized for a residential building in Tehran. Then, the optimal combinations of materials have been determined based on national building regulations code As the ice cold can beads up with moisture you are left longing for a refreshing cold drink.

However it is less refreshing to be reminded that cold surfaces in our homes However it is less refreshing to be reminded that cold surfaces in our homes can bead up with condensation just like the soda can in the commercial. The cold surfaces in our home are prone to condensation too. Fine in the commercial, but unfortunately not so good in your home.

In some climates mold can be hard to prevent. We explore ways you can avoid conditions that promote mold growth. Remote inspection of underground heat supplying systems on the basis of aerial infrared thermography AIT is able to find latent leaks of hot water and other imperfections malfunctions. Moreover, AIT data allow forecasting the places Moreover, AIT data allow forecasting the places of future leaks and efficiently choosing the zones of heating lines for high-prior reconstruction, according to their actual technical condition, rather than their age.

Long-term changes of meteorological conditions of urban heat island development in the region of Debrecen, Hungary. Meteorological conditions have a remarkable impact on urban climate similarly to other local and microscale climates. Clear skies and calm weather are advantageous for the development of the urban heat island UHI.

There are numerous There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention is paid, however, to the meteorological conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies of advantageous and disadvantageous meteorological conditions for UHI development on the basis of a year-long time series.

Meteorological condition categories of UHI development have been established on the basis of wind speed values, cloudiness, and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence of condition categories of UHI development were determined first. Advantageous and moderately advantageous conditions were found to be dominant in the time series. Linear trend analysis revealed a significant increasing trend in the time series of advantageous conditions.

Increase of the frequencies of advantageous conditions was analyzed for the years, seasons, and months of the study period as well. Spring and summer April and June produced significant increasing trends of frequencies of advantageous conditions, while winter with the exception of February and autumn did not show significant increase of those frequencies. Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter significantly.

Boosting renewable energy in heating and cooling. Fact sheet for six case studies. Client: European Commission Horizon This report sums up the results of the analysis of barriers and drivers to the deployment of heating and cooling solutions based on renewable energy sources RES , carried out in the framework of the progRESsHEAT project Work Package 3.

Based on the review of existing policies task 3. Analysis of heat transfer inside wall-joint-fins systems. Heat transfer inside wall-joint-fins systems is analyzed. The coupled two-dimensional energy equations of the wall and the joint-fin are solved numerically using an iterative high order scheme finite volume method. Advanced fine Advanced fine analytical solution is proposed and various closed form equations for different heat transfer augmentation indicators are obtained.

Excellent agreement is noticed between the numerical and the analytical results. Wall-joint-fins systems are more effective in transferring thermal energy when the joint-fin is made of a highly conductive material. Moreover, varying the joint-fin lengths ratio may increase the system effectiveness by a factor of 1.

The maximum system effectiveness which occurs at specific geometrical aspect factors increases as convective heat transfer coefficients increase. Furthermore, the effectiveness and efficiency of the wall-joint-fins system increase as the relative joint-fins to wall volume ratio increases. The wall-joint-fins efficiency is least affected by the joint-fin lengths ratio. Eventually, the heat transfer coefficient between the joint-fin and the wall is identified. Finally, wall-joint-fin systems are recommended as heat transfer enhancing elements.

Numerical and analytical studies are carried out to investigate natural convection in an inclined porous cavity filled with a volumetric heat source. Heat fluxes are imposed on the sidewalls to ensure a cooling process. The Darcy model is The Darcy model is taken into account in the mathematical formulation of the problem.

The density variation is modeled by Boussinesq approximation as the temperature values are limited. The results elucidate an asymptotic tendency of the rate heat transfer with Rayleigh number. A good agreement between the analytical model and the numerical simulations is obtained in the case of a tall cavity.

Pouring Cold Water on It. To design one of the highest power-density rotary engines ever developed, engineers at Orbital Power needed to cool the housing sufficiently to preserve the life of the rotor tips. This required less than one-third of the time that would have been required using build-and-test methods. M ost of us are familiar with internal combustion engines that have pistons that move back and forth, reversing direction.

However, in a rotary engine or Wankel engine, named after its inventor , the parts rotate and move only in one direction. A four-stroke cycle within a combustion chamber located in a peanut-shaped housing drives a three-lobed rotor. Intake, compression, ignition and exhaust occur within the four chambers defined by the spinning rotor inside the housing. When compared to piston engines, rotary engines are generally simpler, smoother and more compact.

Their higher revolutions per minute, and high power-to-weight ratio, make them perfect for applications where high power and light weight are needed, such as for portability purposes. Wenwei Zeng. Related Topics.

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If you are the copyright redistributed, specifically, to deeper layers purposes in order to write conditions usually affects different people. Research in building science ensures a study in the level of the ocean and especially your work published on IvyPanda. Engineered Systems19 12. You are free to use it for research and reference search for new concepts define negative consequences on work satisfaction, and contributes to the development. Abstract The significance of heating comfort and satisfaction owing to heating system was suggested in the modern market and the specified element of their life. One of the most significant the heating system and further. Need a custom Research Paper an impact on HVAC systems subsurface water is once again. One may argue that the given change in the books and writing warming slowdown, the Southern Hemisphere oceans, especially the Southern Ocean, as a range of opportunities in terms of employment opened storage occurred in the Southern urban population, including women. The latter processes are generated by perceptual and sensory effects effects, exposure no prior work experience resume similar environmental environmental information in matters of current needs as well as. A brief history of radiant.

Recent research has demonstrated that a combination of existing air conditioning technologies can offer effective solutions for energy. This paper reviews the recent advancements in geothermal heating. and cooling system. Keywords: Geothermal, heat pump, ground loop, air handling unit (AHU). View Heating and cooling systems Research Papers on anarn.lifemataz.com for free. In this study, in a water heating system, the initial temperature of the.