Abstract: The design method of heat pump air-conditioning system: air-conditioning load and capacity determination, unit type and number of units, heat pump position, pump selection and arrangement, heat pump air conditioning system terminal equipment selection.

Keywords: air conditioning load heat pump air conditioning end equipment 1, air conditioning load and capacity determination

Air conditioning load includes air conditioning cooling load and air conditioning heat load. Air conditioning cold (hot) load refers to the indoor air parameters to maintain the design parameters, the unit of time to be provided to the building cold (heat). This is a variable that is affected by many factors, such as interior design parameters, indoor personnel, equipment, etc., heat dissipation, water loss, nature of the envelope structure, outdoor air environment parameters (including temperature and humidity, airflow velocity, etc.) and solar radiation intensity. Air-conditioning cold (heat) load under indoor and outdoor design calculation parameters Calculate the cold (heat) load for the air conditioning design of a building. It is the fundamental purpose of air conditioning design that the air conditioning system appropriately provides the quantity of cold (heat) to meet the demand of the building under the design and calculation conditions and adapt to the cold (heat) load of the building air conditioning and its changes at any time.

In the process of air-conditioning system design, air-conditioning load calculation is the first step, air-conditioning load calculation should include air-conditioning design calculation of load and load analysis of each period. Second, the capacity of the equipment must meet the requirements of cold (heat) load calculation of air conditioning design, while the other equipment configuration should be adapted to the characteristics of air conditioning load changes. In the air source heat pump type chiller unit for the cooling air conditioning system design heat pump unit capacity must take into account the building at the same time each part of the coefficient, should also take into account the actual heat pump heat capacity, the actual heat will be due to Equipment spacing restrictions and other causes of poor ventilation, part of the airflow short circuit (this part of the output loss of about 5%) are affected, and the outdoor heat exchanger due to surface ash, heat exchanger surface scaling, equipment attenuation and other factors Impact, so the choice of heat pump units should still consider the safety factor. By the formula to indicate:

Q = β1 · β2 · QD.

Where, Q - heat pump unit in the design conditions of cooling (heating) KW

QD - design calculation load, KW

β1 - simultaneous use of coefficients, determined by the specific project, generally 0.75 to 1.0

β2 - safety factor, generally take 1.05 ~ 1.10.

In addition, heat pump units not only meet the cooling requirements of the system in summer, but also to meet the system requirements of winter air-conditioning heating. Different suppliers of heat pump rated cooling capacity, rated heating capacity of the different parameters, and outdoor air conditioning in various regions of the design parameters are not necessarily consistent. For Nanjing, the rated cooling conditions of the heat pump units provided by the general suppliers are the same as or close to those of the actual ones. Generally, the air dry-bulb temperature is 35 ° C and the air-conditioning refrigerant water inlet and outlet temperatures are respectively 12 ° C and 7 ° C. The winter heat pump rated working conditions for the outdoor air temperature 7 ~ 8 ℃, inlet and outlet water temperature is 50-55 ℃. This condition and Nanjing winter air conditioning design and calculation of the temperature is far from. Nanjing climate is characterized by cold winter and hot summer. For general office, hotel-based complex building, winter air conditioning heating design calculated thermal load of about 70-85% of the summer air conditioning design calculated cooling load. In the heat pump unit selection, you should see the heat pump unit corresponding to the local design and calculation of meteorological parameters of the real output. If the heat pump unit in the design and calculation of outdoor parameters of the cooling capacity is greater than the calculated design cooling load, and the heating capacity is equal to the thermal load, the heat load should be subject to select the heat pump. Conversely, if the cooling capacity to meet the design and calculation of cooling load requirements, while the heat is greater than the required heat, you may consider some of the selection of air-cooled chillers, some of the selection of heat pump units to reduce investment. Under normal circumstances, selected by the heat load in summer, to meet the requirements of winter heating.

2, the type and number of units to determine

Heat pump water chiller units can be divided into different types according to the compressor scroll heat pump unit, reciprocating heat pump unit and screw heat pump unit, according to the size of the unit structure, the combination of different sizes, heat pump unit can be divided into integral heat pump units and modules Heat pump unit.
The integral heat pump unit and the modular heat pump unit is no essential difference, the so-called modular heat pump refers to a heat pump unit by a number of heat pump unit (an independent refrigeration circuit, independent evaporation, condensation, independent framework, and even independent Control panel) made in parallel, the combination of various units flexible and convenient combination of any one unit failure does not affect the rest of the unit's work. The rated cooling capacity per unit is about 55KW. The domestic heat pump manufacturers to produce modular heat pump units as much, and the overall heat pump unit is a combination unit from the appearance, a whole framework, although there may be more than one compressor, and even more than two refrigeration circuits, However, they can not be further decomposed. The main advantages of modular heat pump unit is low noise, small vibration, due to the system of the total refrigeration circuit, the winter frost on the system temperature little effect. In addition, the heat pump unit is usually placed on the roof. The modular heat pump unit has the advantages of convenient transportation, convenient installation due to the flexible combination of various units and small size and light weight of each unit. If the project is large, modular heat pump unit will be due to the large number of refrigeration units, and there are many points of failure, the maintenance of large capacity may be slightly lower than the rated efficiency of the overall unit. In addition, due to the modular heat pump plate heat exchanger is generally used, the higher the water quality requirements of the hydraulic equilibrium between the units is also higher. In summary, for smaller systems, or size, weight lifting and other special occasions, the modular heat pump has its advantages. The selected modular heat pump should pay attention to three issues: First, the water quality requirements, the entrance to set a higher filtration efficiency of the filter, and second, the hydraulic balance is better, the third is the number of pieces should not be assembled too much, so as not to affect the heat exchanger into the wind area. In general, a group of not more than 6 units. In the selection of integral heat pump units, air conditioners should take into account the characteristics of load changes and equipment interoperability between equipment, taking into account the winter heat pump defrost minimize the impact on water temperature. Generally, the number of heat pump units of an air-conditioning system should not be less than 2-3 units, and the total number of refrigeration circuits of the heat pump units configured for each air-conditioning system should not be less than 4-6. Of course, the number of heat pump should also consider the building functions, user unit division, measurement, management and other comprehensive factors. To the reciprocating heat pump units and screw heat pump units, in theory, screw-type heat pump less moving parts, less maintenance, high efficiency, low noise. However, due to the heat pump is a large part of the noise from the fan, and compressor noise can be reduced by adding noise enclosures, etc., so in fact screw-type heat pump noise slightly lower than the piston-type heat pump noise (about 3-5dB (A) ). In addition, the heat pump unit heat resistance is mainly in the outdoor heat exchanger side, the heat pump efficiency is also affected by the two-area and other factors, so from the engineering point of view, screw-type heat pump and piston-type heat pump in the difference in efficiency is limited. However, the price of screw heat pump than the reciprocating heat pump. On the refrigerant issue, when possible, as far as possible the choice of environment-friendly refrigerators, such as R134a, R407C, which should be preferred R407C followed by R134a, from the price of the refrigerant, the cheapest is R22.

3, the location of the heat pump

The location of the heat pump has the following several, one is placed in the top of the podium, the second is placed in the top of the tower, the third is placed on the windowsill, the fourth is placed in a high net indoor height. Taking into account the lifting and replacement of other reasons, the heat pump is more placed in the top of the podium. When the heat pump is placed on the top of the podium, it is necessary to evaluate its impact on the main building and the surrounding environment. Larger heat pump units (≥ 200RT) and stand-alone noise of 75 ~ 85db (A) or so. If necessary, add noise barriers, or in the main building by heat pump to avoid the door to do double-glazed windows or high-quality hollow glass instead of ordinary single-pane glass. Heat pumps arranged on the windowsills are often independent configuration of each floor, separate measurement of places, only limited to the smaller capacity of the heat pump, the exhaust side should be used in the form of side into the wind. Selection of exhaust heat pump should be installed when the diversion duct, into the side of the exhaust. Even if there is a high clearance in the room, it is not advisable to place the heat pump in the room. When the conditions are limited, the indoor air should be used in the hallway. There should be enough air inlet area and ventilation through the air duct To the outdoor, to prevent short-circuit airflow. When adding exhaust pipe, the fan should be adjusted accordingly to avoid the increase of resistance and reduce the ventilation. Ideally, heat pumps should be placed on top of the tower so that the heat pump has good ventilation and minimizes noise impact. . However, it should be noted that the heat pump can not be located near residential or other noise-demanding rooms. Heat pumps and water pumps should not be placed above or below the residence (guest room). Heat pump unit should adopt spring shock absorber vibration isolation, shock absorber model and layout points are determined by calculation. Heat pump by the daughter of the wall and the main building distance greater than 3m, heat pump spacing should not be less than 3m, when the distance should be increased. In addition to consider the layout of the heat pump around the small, good ventilation, but also consider the pipeline layout, lifting equipment and subsequent replacement and other factors, when conditions set aside 1 to 2 heat pump position, leaving room for development and equipment Install and replace Consider adequate load conditions.
4, the choice and layout of the pump

The number of pumps should correspond to the number of heat pumps. Heat pump and pump connection should adopt a one-on-one way, heat pump and pump linkage. When the number of heat pumps is more, the pump can be affixed to the heat pump arrangement, the water pump should have a waterproof performance and add the rain cover, when the heat pump is small, the pump should be arranged in the room. Standby pumps can be used without first installing a temporary replacement method. If the pump is connected in parallel with the parallel first heat pump in series, the number of parallel heat pumps should not exceed 6 and there should be reliable hydraulic balance measures. This connection should be arranged in the pump near the heat pump room can also be placed in the basement, the number of pumps should be considered 1 to 2 spare pump. In the selection of pump specifications, as far as possible choose a low speed pump, to reduce noise, the pump flow rate can be selected according to the system 1.1 times, the pump lift should be equal to the system to overcome the total resistance. Pump power consumption should be controlled within the heat pump output within 1/30. The layout of the pump to have a certain distance, when conditions reserved for the installation of 1 to 2 pumps for development needs. Pumps should also have reliable vibration isolation measures.

5, heat pump air conditioning system end equipment options

Under summer conditions, the rated return water temperature of the heat pump unit is 7 ℃ and 12 ℃ respectively, which is consistent with the rated condition of the general air conditioner. The calculation and selection of the air conditioner is consistent with other forms of air conditioning systems. Winter working conditions, heat pump air conditioning system rated conditions (outdoor air 8 ℃), heat pump rated supply and return water temperature are generally 47 ℃, 42 ℃. When the outdoor temperature is low, the heat pump air conditioning system, the water temperature is generally maintained at 39 ~ 40 ℃. The water temperature is obviously lower than the rated heating and cooling water supply system temperature (60 ℃ and 50 ℃, respectively), which is lower than the rated inlet and outlet water temperature of the general air conditioner performance parameters (also respectively 60 ℃ and 50 ℃), due to water temperature is not the same, there is a significant difference between the amount of heat the air conditioner. Some scholars think that heat pump air conditioning system end equipment should be calculated based on the results of the summer conditions based on the results have been enlarged. However, according to our calculations, the end of the heat pump air-conditioning system in Nanjing can be calculated using the results of the calculation under summer cooling conditions. On the one hand, the heating load of general buildings in Nanjing area is less than that of summer cooling load. In addition, with the same air conditioner, the heat supply under 60 ℃ water inlet temperature is obviously greater than the cooling capacity under water inlet condition of 7 ℃ . In winter when the water temperature dropped to 39 ~ 40 ℃, the heat capacity of the air conditioner to meet the requirements of indoor heating. In addition, accustomed to select mid-range air conditioner parameters, itself has some margin. If the heat pump air conditioning system has more than 4 refrigeration circuits, defrost on the water temperature will not cause significant fluctuations, it will not affect the indoor temperature fluctuations. However, when the system heat pump only 1 or 2 circuits, in order to reduce the impact of frost on the indoor temperature, when conditions permit, you can start and stop the air conditioner control and water temperature synchronization, such as when the water temperature is below 35 ℃, the air conditioner fan stop Operation, when the water temperature is higher than 35 ℃ fan to resume operation. This can effectively improve indoor comfort.

6, heat pump air conditioning water system

Larger air-conditioning systems, or buildings with different operating hours of different functional parts, or a number of parts to be measured independently, or there is a large part of the resistance difference, the air-conditioning water system should be divided into several sub-systems by sub-catchment , Heat pump and pump configuration should be adapted to ensure that the system is always in a state of higher work efficiency. System partition should meet the requirements of each part of the measurement and maintenance, should meet the different functional parts of the different requirements of the operation, to the extent possible, the same nature of the air conditioner attributed to a subsystem, and the resistance characteristics of large air-conditioners Such as fan coil air conditioners and modular air conditioners, or fan coil air conditioners and fresh air units, etc.) are divided into different subsystems. The system equipment as long as conditions permit, the same way as possible with the same layout. Parallel connection of the pump, parallel heat pump or parallel pump - heat pump group connection between the same way as much as possible with the same layout, the different water system should be connected through the manifold, manifold should be set in the manifold on the thermometer And balance valve. The parallel loop of the return pipe when conditions should also be set thermometer and balance valve to facilitate observation and hydraulic balance. The main equipment (heat pump, modular air conditioner, cabinet air conditioner) into the mouth should be set thermometer, soft joints, filters, pressure gauges.
System heat pump and pump connection should adopt the press-in connection, that is, water pump to the heat pump. Not far from the pump and heat pump, you can only install the filter suction pump. Heat exchanger with a plate heat exchanger inlet should be installed not less than 60 /? Grave? Ao W 楹 fresh Jiaozhan patella Ao ⒐ 袷 Jiao patella 鹘 Mo like? Knock 诘 M 缁? Tan Yun patella chameleon Mo mo mo ?? like a ⑺ ⑺ 绞 lower twist 姆 坦 坦 坦 坦 诿 stunned the stomach 艽 艽 似 似 like Ao K?鋈 oxime 诰 Put 低 O low ㄑ pull ㄑ 阌 阌 阌 栌 骰 Dice Si 苌 thin O low support 蛘 retreat 涞 son 叱 叱 squid low key Gang knock? M above. Water tank above the living water tank, the pump should be used to make up water. Expansion tank should be set signal tube in order to observe the water level. The location of expansion tank should be avoided due to various reasons, the overflow may cause impact on the elevator. Conditionally conditioned air conditioning system should adopt variable water control to effectively solve the hydraulic imbalance and reduce pump consumption under partial load conditions. When the system heat pump and the pump connected in parallel with each other in parallel before the way, in order to reduce the pump consumption, the heat pump outlet should be installed with the heat pump unit linkage electric valve.

7, to reduce the noise of heat pump measures

To reduce the impact of heat pump noise, on the one hand should start with heat pump units, such as compressors and muffler sets, fans with silent type, that is, as far as possible the selection of low noise heat pump units. Heat pump unit in addition to its own internal compressor seat has a good damping, heat pump machine base should also have damping measures, as far as possible the choice of spring shock absorber, spring shock absorber should be carefully calculated. In addition, heat pump units should be located as far away as possible from the room or between adjacent rooms in the layout, provided that the sound insulation screen should not obstruct the ventilation of the ventilation air flow. In general, the heat pump unit layout in the main roof of the smallest impact surface. Going from the building to the heat pump where the roof entrances and exits should be made of sound insulation doors and sound insulation suites, or between the heat pump unit and the building core tube auxiliary room (such as pumps, power distribution room) and other partitions. Pump is also the main source of noise, pump noise damping equally important. Put on the roof of the pump should be set with a spring balance weight balancing block pedestal. Conditions of the pump placed indoors, both rain, but also noise, pump should be made of sound-absorbing treatment, such as water pumps placed outdoors, rain cover affixed to the sound-absorbing material noise reduction effect. In addition, the pump should use low-speed pump, pump room leading to the inside of the door should be made of sound-insulated doors, noise barriers provided when conditions.

8, air-source heat pump air conditioning system energy-saving measures

In the case of heat pump air conditioning systems, the rated power consumption exceeds 50% of the rated power consumption of the entire building. Effective energy-saving measures for air-conditioning system for reducing building energy consumption and reduce the operating costs of the building have obvious effect and significance. Heat pump air conditioning system part of the power consumption: heat pump units including compressors and cooling fans, air conditioners, water pumps. Energy-saving measures for heat pump air conditioners can be divided into the following areas.

(1) Selection of high efficiency and low energy consumption heat pump, a reasonable number of heat pump units.

In the heat pump air-conditioning system, the power consumption of the heat pump unit under rated cooling conditions accounts for 78-90% of the total energy consumption of the air conditioning system (depending on the form of the terminal air conditioner), and the energy consumption of the compressor accounts for about The total energy consumption of 74 to 84%, fan energy consumption accounted for 4 to 6%. Therefore, the level of heat pump efficiency on the air conditioning system has a decisive role. The efficiency of the heat pump unit includes the efficiency under rated conditions and the efficiency under partial load conditions. Judging from the information provided by each supplier, there are obvious differences in the efficiency of the heat pump, the highest rated cooling coefficient of about 3.7, the lower about 2.8. Energy-efficient heat pump with significant significance. Individual heat pump can also change the fan speed according to the outdoor environment parameters to reduce fan energy consumption. The air conditioning load of a building varies with the changes of the external meteorological parameters and the internal usage conditions. The number and size of the heat pump units should fully consider the characteristics and efficiency of the full load efficiency and the partial load, and the optimized energy consumption is the lowest throughout the year. In principle, no less than 2 to 3 heat pump units, the number of independent refrigeration cycles of not less than 4 to 6.

(2) Reasonable matching pump

Under the rated conditions, the energy consumption of the pump accounts for about 5 ~ 9% of the total energy consumption of the air-conditioning system. Under partial load conditions, if the mismatch is improperly selected, the energy consumption of the pump will not decrease and the proportion of the total system energy consumption will be obviously increased .
In addition, the project generally occurs in the selected pump is too large, the water temperature difference is too small. Therefore, there is great potential for energy saving on the pump side. As many pumps as possible with the number of heat pump units match, so that part of the heat pump shutdown, the pump downtime, in order to reduce the pump consumption. The selected pump should also be efficient pump, the required flow of the pump, head should be consistent with the actual. In addition, if the pump can use variable frequency pump, so that the rated conditions of the water temperature difference of 5 ℃, at the same time under partial load, the pump flow accordingly changes, of course, not less than the minimum heat pump unit flow, the energy saving effect will More significant. Using frequency conversion technology to transform existing projects promising.

(3) using automatic control method

Under partial load condition, it is necessary to control the heat pump units in a reasonable way when the heat pump units are put into operation. To make the running number of the pumps synchronized with the heat pump units, the system needs to be controlled by the variable water volume. Allowing the pump to change its volume within a limited range also requires reliable heat pump and pump control. The organization and control of fresh air volume (fresh air volume control based on outdoor environmental parameters or carbon dioxide concentration) can minimize the fresh air energy consumption, and sometimes use outdoor fresh air for natural cooling to minimize the energy consumption.

(4) end air conditioner energy saving

The energy consumed by the end air conditioners accounts for about 5% to 17% of the total air conditioning system energy consumption. When the end air conditioners are fan-coil-based, their share of energy consumption becomes smaller and the combined air conditioners are dominant , The proportion of its total energy consumption increases. Therefore, from the perspective of reducing energy consumption, small and decentralized air conditioners are more energy-efficient. In addition, high enthalpy low air volume air conditioner less power consumption than the low enthalpy difference air volume air conditioner. Air conditioning organizations without strict requirements of the comfort of air conditioning places, especially shopping malls and other staff gather more places, large enthalpy air-conditioners can reduce energy consumption, but also reduce the air duct area, save the air duct system investment and construction space. General cabinet, modular air conditioner often have four rows of tubes, six rows of tubes and eight rows of pipe points. From the perspective of saving as little as possible with four rows of pipe air conditioners, multi-six air-conditioners, the combination of air conditioners can be considered with eight rows of pipe air conditioners. In addition, due to the energy consumption of air conditioners accounted for a lot of weight, under partial load conditions, as much as possible to reduce the energy consumption of air conditioners have obvious value. Regardless of the water system is changing the amount of water, air-conditioners set gear transmission is required. In the fixed water system, the conditions of the air conditioner using frequency control method such as constant temperature control to minimize the energy consumption of the end air conditioner. Adopting the air conditioning system as the standard metering air-conditioning system, wind speed control can make measurement more objective. The energy saving of the end air conditioner can also be embodied in that outdoor air is used to cool the indoor air as much as possible when the outdoor air enthalpy is lower than the indoor air enthalpy. Dual air-cooled unit air-conditioner system or discrete but linked control of variable fresh air and variable exhaust system can achieve this effect.

(5) improve the environment ventilation, to prevent short-circuit airflow

Ventilation of the environment in which the heat pump is located is a very important condition for the heat pump to operate efficiently and even for normal operation. Well-ventilated standard is that the air entering the heat pump is ambient air, while the heat pump exhaust air flow can be discharged in time, far away, heat pump exhaust and suction is not short-circuit. In order to achieve this goal, efforts should be made to provide a sufficient distance between the heat pump and the wall of the daughters, or a sufficiently large area of ​​the vents on the wall of the daughters. Secondly, the heat pump should have sufficient distance from the core drum and the main building, A certain distance of space, these distances should generally be 3 meters above. In order to beautiful and convenient layout, heat pump units are mostly aligned side by side layout, in order to improve ventilation, heat pump units can be wrongly listed. In addition, attention should be paid to the influence of wind direction, as far as possible to avoid the heat pump unit is arranged in the main wind direction 45 degrees dark area of ​​the building. When the heat pump unit side by side, between the heat pump to take the rafters can be more effective in reducing short circuit, and the other can improve the suction environment, the winter rain and snow to reduce the degree of accumulation of frost have a good effect, this measure can also reduce the summer heat pump Inhaling the temperature of the air stream reduces the adverse effects of solar radiation on the surface temperature of the heat exchanger. Under the grill can set the pump, but also for the daily inspection and maintenance to create a good environment.

Heat pump unit should not be placed indoors, not arranged in the alignment of the balcony on each floor. Such as arranged on the balcony, the balcony should be outstanding overall plane, should be located in a well ventilated corner, should choose the side of the exhaust form, or the vertical exhaust heat pump plus duct horizontal exhaust, but the fan should be adjusted accordingly. Had to be placed in the indoor heat pump must be connected to the exhaust pipe, the exhaust leads to the outdoors, and to avoid the exhaust outlet and inlet too close to form a short circuit phenomenon. Also due to add air duct, heat pump with fan should be adjusted to the new ventilation conditions.
The airflow around the heat pump is complex and the airflow can be modeled by computational fluid dynamics to find the best possible ventilation arrangement.

(6) ventilation and energy saving

Fresh air load accounts for a considerable proportion of air-conditioned buildings, rated operating conditions, office, hotel and other buildings accounted for about 30% of the total load of air conditioning, commercial buildings, fresh air load accounts for about 50%. The amount of fresh air is equal to the sum of the amount of exhaust air and infiltration wind and intrusion wind. The infiltration of wind, invasion of wind down to a minimum, to organize the exhaust through the total heat exchanger to recover the energy, with significant energy-saving significance. Due to the current domestic poor air quality, air dust content, to the total heat exchanger management troubles, but also shorten the useful life of the total heat exchanger, thus affecting a large number of total heat exchanger promotion. For heat pump air conditioning systems, such as exhaust ventilation organized to the heat pump unit entrance, but also help to improve the efficiency of heat pump units, after all, a simple and effective energy-saving measures.

(7) other measures

In the hot summer, many engineering heat pump units due to poor ventilation or quality problems on the unit, the water temperature is difficult to be guaranteed, in which case the inlet side to the heat exchanger water spray method can receive significant results. The adverse consequences of water spray may cause heat exchanger surface fouling, which affects the heat transfer, but due to the coil surface has some dust, scale may not be formed directly on the coil surface and even affect the extent of heat transfer. In order to prevent fouling, spray softening water is the fundamental solution to the problem, but will increase the cost. In order to improve the efficiency of water injection, we should change the water spray, spray just how much, how to spray the highest efficiency, non-soft spray any adverse effects and the extent of their impact are worthy of further study.

(8) operation and energy saving

From the heat pump characteristic curve discussed earlier, it can be seen that the change of the outlet temperature of the heat pump unit can change the efficiency of the heat pump unit. For example, when the ambient temperature is 30 ℃ and the temperature of water is 12 ℃, the efficiency of the heat pump unit is 6% higher than that of the outlet water temperature of 7 ℃. When the ambient temperature is 30 ℃ and the outlet water temperature is 15 ℃, the efficiency of the heat pump is the outlet water temperature 1.07 times at 7 ℃. Changes in water temperature will reduce the end of the air conditioner heat transfer efficiency, but under partial load conditions, the appropriate lower temperature can also meet the indoor requirements. Similar results were obtained in winter, when the outdoor temperature was -6 ° C (the outdoor calculation temperature of the air conditioner design in Nanjing), the efficiency of the heat pump unit when the water temperature was 40 ° C was about 13% higher than that when the water temperature was 50 ° C, At 0 ℃, the heat pump unit effluent temperature 40 ℃ effluent efficiency is 1.14 times when 50 ℃. Nanjing and similar weather conditions in the region, the winter 40 ℃ water temperature to meet the end of the air conditioning heating requirements.

In addition, the air-conditioning system is turned on in advance before workers arrive, which is good for energy saving. In addition, due to the heat storage characteristics of the envelope and furniture, the air-conditioning system heat pump unit shut down half an hour earlier than after get off work hours to 1 hour without affecting the whole Comfortable, there are obvious energy-saving effect. Early boot, the exact shutdown time in advance the exact time based on building envelope structure, interior furniture features, the use of features and other factors, depending on the project generally about half an hour ahead of schedule, stop the heat pump program is feasible.

Defrost is the heat pump unit can not be the action of defrosting not only during heating, but cooling, heating efficiency significantly. Improving the defrosting control mode and improving the accuracy of the intelligent defrosting control system are one of the important topics for improving the performance of heat pump units. In the operation and management of the heat pump adopting the non-intelligent frost controller, the administrator can adjust the defrosting clearance and the defrosting time according to the climate change at any time according to the climate characteristics, which can obviously improve the heat supply efficiency of the heat pump unit and reduce the energy waste.

In addition, the combination of heat pump and storage air-conditioning technology can play a role in peak load shifting and gridding, with obvious social benefits and good market prospects. Recycling of heat pump condensing heat should also be manufacturers, owners, engineers concerned about the energy-saving issues.

In short, the heat pump air conditioning system is widely used, saving a lot of space, considerable savings in energy. Promote energy-saving technologies to improve the existing heat pump air-conditioning system, optimize the design of new heat pump air-conditioning system, can save huge energy, with significant economic, energy efficiency, environmental and social benefits.

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