Abstract: In this paper, a "air-source heat pump system of refrigeration, heating and sanitary hot water" for small-scale central air-conditioners is put forward according to the actual situation, which can provide domestic sanitary hot water by using the condensation heat of the air conditioner. The system can be connected with the domestic central hot water system. This article also discusses the design of the system components to amend, and the system for the annual operation analysis. Keywords: small central air-conditioning heat pump hot water heat recovery 0 Introduction In the face of the world are facing more and more warming energy crisis in front of our country as a large energy-consuming countries, the energy utilization rate is still not high, but with various national policy incentives, Limitation, promotion of incentives, people pay more and more attention to energy conservation. In the balance of energy budget, heat loss accounts for a large part of the air conditioning system condensing heat belongs to the low temperature waste heat, easy to use and from the perspective of enthalpy, heat loss is not large. In our country, the central air conditioner generates a large amount of condensation heat during operation, which is discharged into the atmosphere in vain, resulting in the loss of available energy. At the same time the central air conditioning with the hotel, the hotel need to provide hot water throughout the year, the general use of steam water, due to the winter high summer low demand, designed according to the needs of winter hot water boilers in the summer are often at low load operation. If you can recover the heat of condensation to generate hot water to meet the hot water demand in summer, to share the boiler heat supply and reduce energy consumption in winter will be an energy-saving way to turn waste into treasure. 1 System 1.1 without cooling heat recovery air-cooled chiller cycle Figure 1 with fully enclosed reciprocating compressor air-cooled heat pump unit lgp-h Figure 1, 2 to 5 points for the entire process of condensation, of which 2 to 3 points is the refrigerant superheat segment to show sensible heat, 3 to 4 points refrigerant latent heat, 4 to 5 points is the sub-cooling section put sensible heat process. Operating in cooling conditions, 4 ℃ evaporation, 49 ℃ condensation, 5 ℃ inspiratory overheating, 5 ℃ throttling cold, condensation heat up to 1.15 to 1.3 times the refrigeration capacity. Isentropic, the compressor discharge port t2s is about 70 ℃, in fact, the compressor exhaust overheating, t2 can reach about 83 ℃, it is possible to provide 55 ~ 65 ℃ domestic hot water. Taking R22 as an example, the low-temperature waste heat that can be recovered per unit of refrigerant is 2-3 stages of heat, accounting for about 17% of the condensation heat. The remaining condensable liquid of the liquid phase is still larger than the 6-1 evaporable heat, Part of the heat is recovered, the winter can still meet the thermal load design. 1.2 with heat recovery of air-cooled chiller 1.2.1 The heat recovery unit of the device: 1. Compressor 9. Thermal expansion valve 17. Descaling device 2. Electromagnetic three-way valve Check valve 18. Water pressure sensor 3. Heat recovery heat exchanger 11. Check valve 19. Air conditioning water temperature sensor 4. Electromagnetic four-way valve 12. Check valve 20. Outlet 5. Air side heat exchanger 13. Thermal expansion valve temperature package 21. Intake pipe 6. Fan 14. Gas-liquid separator 22. Domestic hot water outlet pipe 7. Check valve 15. Air conditioning pumps 23. Tap water inlet pipe 8. High pressure receiver. Water side heat exchanger Figure 2 Schematic diagram of heat recovery unit Refrigerant circuit: the exhaust port of the compressor 1 in turn connected to the four-way valve 4, air-side heat exchanger 5, check valve 7, high pressure receiver 8, heat The expansion valve 9, the check valve 11, the water-side heat exchanger 16, the four-way valve 4, the gas-liquid separator 14, and then back to the suction port of the compressor 1 are connected to the outlet of the check valve 11 and the outlet of the check valve 7 A check valve 12 is arranged between the four-way valve 4 and the gas-liquid separator 14 in the connecting line between the four-way valve 4 and the gas-liquid separator 14; 1.2.2 Characteristics of the heat recovery unit (1) A heat recovery heat exchanger is arranged between the exhaust port of the compressor of the device and the inlet of the four-way valve, the exhaust pipe of the compressor is connected with the inlet of the refrigerant passage inside the heat recovery heat exchanger, the heat recovery heat exchange The outlet of the device is connected with the inlet of the four-way valve, and the entrances and exits of the domestic hot water passage are respectively connected with the inlet of the domestic hot water inlet pipe and the heat recovery heat exchanger water passage. (2) an electromagnetic three-way valve is arranged between the exhaust port of the compressor of the air conditioner and the heat recovery heat exchanger, the inlet of the electromagnetic three-way valve is connected with the exhaust port of the compressor, and the other two outlets are respectively connected with the four The inlet of the through valve is connected to the inlet of the heat recovery heat exchanger refrigerant passage, and the outlet of the heat recovery heat exchanger refrigerant passage is connected to the inlet of the four-way valve. (3) In order to solve the problem of easy fouling of the domestic hot water pipeline in the traditional scheme, in addition to adding a descaling device in the hot water pipeline, an electromagnetic tee is provided between the exhaust pipe of the compressor and the heat recovery heat exchanger Valve, the use of electromagnetic three-way valve to convert the flow of high temperature refrigerant in the hot water unit is not running hot water, high temperature gas refrigerant without heat recovery refrigerant directly bypass into the electromagnetic four-way valve to avoid high temperature Gaseous refrigerant will continue to heat the water in the heat recovery heat exchanger to cause hot water pipeline fouling. 2 Components 2.1 Compressor The heat recovery unit compressor selection and ordinary air-cooled hot and cold water units, that is, according to various types of compressor cooling capacity and evaporation temperature, condensation temperature curve (performance curve) generally Provided by the manufacturer. If there is no performance curve as a reference, according to compressor product samples provided by the gas selection. As mentioned earlier in this paper, the amount of heat that can be recovered theoretically can reach 17%, but in actual operation, because the heat exchange side is the gas phase and the thermal resistance is large, plate heat exchangers with high heat exchange efficiency may reach Not so much. To design a 20kW heat recovery unit, for example, according to the general engineering example, the hot water supply required by the hotel is about 20-30% of its cooling capacity [5], a slightly larger capacity compressor may be properly selected, That is, the evaporation temperature and the condensing temperature are unchanged, the cooling capacity is increased to 1.2-1.3 times of the designed load, which meets the heat supply of the hot water. In this article, the design itself is to ensure that the cooling effect as a precondition, as far as possible recovery of waste heat. In the case of large demand for hot water in winter, also need to use auxiliary heat source. 2.2 Air Side Heat Exchanger The design of air-cooled condenser, the heat load is the enthalpy difference of 5 points and 3 points of the refrigerant in Figure 1 (lgp-h), which is smaller than the design heat load of the unit without heat recovery because the partial condensation Heat for heat recovery, heat recovery heat exchanger, so the unit of air-cooled condenser heat transfer area must be no heat recovery unit air-cooled condenser heat transfer area is small. The calculation of winter, calculated from Figure 1 (lgp-h map) can be obtained, the winter 3-5 condensation heat release is still slightly larger than the design load, and the selection of the appropriate enlargement of the compressor capacity to meet the winter The amount of heat. 2.3 Heat recovery heat exchanger Heat recovery unit heat recovery unit, the heat recovery process shown in Figure 1 (lgp-h chart) from 2 o'clock to 3 o'clock process, the high temperature and high pressure refrigerant gas is discharged from the compressor, the The gas sensible heat and tap water are exchanged in the heat recovery heat exchanger to heat the tap water to obtain 55 to 65 ° C domestic hot water. Heat exchange

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