【 Weak current College 】 heat recovery technology principle and its application of cold water units-Power By 【 China power house network 】

1. preface to the first twenty years of this century, China's economy will continue to remain stable in a rapid growth, however the relative shortage of energy has been increasingly restricting economic development bottleneck, this antinomy in the future for a long period of time will exist for a long time, and there are more obvious trends, at the same time, the rapid development of the economy is at the expense of the environment is in, now it's survival of the environment has been overwhelmed. To this end, the State established the "conservation and development and the conservation of priority" of energy policy, and the "scientific development concept," and "a Socialist harmonious society," new development ideas. With the continuous improvement of living standards and increasing improvement of production conditions, production and living environment is made more stringent requirements, these days, various types of chillers have become important implementations, but the accompanying it is immense energy consumption. Therefore, the energy saving should become the common responsibility of society as a whole, is placed in every air conditioner manufacturing enterprises face major issues. 2. single-vapour compression refrigeration cycle compressor absorption from the evaporator of low temperature and low pressure refrigerant gas, compressed into the high temperature and high pressure refrigerants into the condenser, the condensation for middle temperature (30 ° c – 50 ° c) high-pressure refrigerant fluids, an expansion valve throttle buck for low-temperture and low pressure of the liquid refrigerant (practical for gas-liquid mixtures), enters the evaporator absorption cooling medium heat, a low temperature and low pressure of gas refrigerant, back to the compressor, complete a refrigeration cycle. The first law of thermodynamics, k = φ φ 0 + Pin
Type, Pin-compressor compresses the refrigerant absorbed and consumes power;
Φ 0-refrigerant in the evaporator, the heat absorption refrigerating capacity;
Φ k — system through emitting heat from the condenser. 3. heat recovery technology 3.1 heat recovery through emitting principle of unit of the condenser heat is usually cooling tower or cooling fan discharged to the environment, on the need to use hot sites such as hotels, factories, hospitals, etc. is a huge waste and to the surrounding environment has also created a certain amount of waste heat pollution. Heat recovery technology is a way to run a process water chillers to the outside world in a large number of waste recycling, as a user of the final heat source or primary heat source. Compressor discharge of high temperature and high pressure gas refrigerant heat collector before entering, release heat heating water (or other gas liquid substances), and then through the condenser and expansion valve, were in the evaporator absorption cooling medium heat, a low temperature and low pressure of gas refrigerant, return to the compressor. Diagram of heat collector is the heat recovery of the carrier, a heat recovery and transfer functions. According to the first law of Thermodynamics can be the following formula, φ φ k ' + R = φ 0 ' + Pin '
Type, Pin ' — compressor compresses the refrigerant absorbed and consumes power;
Φ 0 ' — the refrigerant in the evaporator absorption of heat, the cooling capacity;
Φ R-refrigerant heat collector release of heat, i.e. the amount of heat recovery;
Φ k '-condensation of refrigerant in the condenser (or cold) gives off heat. 3.2 heat recovery category for thermal heat collector, heat recovery and can be divided into partial heat recovery and heat recovery. Of these, only partial heat recovery recycling part of chillers, heat emissions total heat recovery basic recovery system into the environment of all calories. 3.3 heat collector forms according to the use of different and specific needs of the user terminal, heat collector can take many different forms, such as shell and tube, plate, finned-tube, tube, etc. 4. heat recovery technology in chiller application based on the most commonly used water chillers, generally to water as the heat recovery of media, to produce sanitary hot water free of charge, for example the discussion. The heat recovery technology, heat collector lane through a gaseous refrigerant at high pressure and high temperature (temperature of about 70 °-85 ° c), in high-temperature and high-pressure refrigerant through heat recovery unit at the same time, the use of normal temperature water circulation pump will be fed into the water, heat collector to heat collector in water and high-temperature refrigerant vapors were condensing refrigerant heat, while the water temperature, and then return to the hot water storage tank, pump and storage tank again from the water into heat collector for hydronic heating, hot water temperature is reached. Storage box in the Park's thermal collector repeated heat and ultimately achieve customer-requested water temperature (55 ℃-60 ℃). When the water temperature reaches the set value, the circulating pump stopped working. User through the hot water valve to extract from the storage tank, hot water tank water level decrease once the water appliance automatic water, water temperature at this time, when the water begins to drop down to below the set value, the hot water circulation pump to start running, again through heat recovery for storage tank water circulation heating (if in the operation of chiller), this will ensure that the storage tank of hot water temperature is maintained at a relatively constant. 5. application of partial heat recovery because only recycling a chiller is running some heat emitted, and therefore the heat collector of refrigerant remains after gas or gas-liquid mixture, in order to guarantee full condensing refrigerant and the cold, cold by water or air cooled condenser condenser condensation of further, there are still some waste heat into the atmosphere. Of course, as is the partial heat recovery, so hot water temperature is relatively high, theoretically infinite close compressor discharge temperature, usually up to 60 ℃ or even higher, effectively meet the day-to-day needs of hot water.
Total heat recovery basic recovery the compressor discharge of all waste heat (minimal heat through compressor shell and exhaust pipe dissipation to the outside environment), which is the total heat recovery, preparation of hot water temperature is relatively low partial heat recovery (normally 30 ° c – 50 ° c), you can implement a water cooled chiller cooling water pumps, cooling fan or air cooled chiller fan stopped working. Of course, heat recovery, cooling water pumps, cooling fan or condensing fan continues to work, the equivalent of the devices from thermal outflow of liquid refrigerant further cooling, thus enhancing the efficiency of the COP value, proved that the COP value generally increases of 3%-5%. 6. closing remarks by application of heat-recovery technology, on the one hand it reduces chiller is running a large number of heat emissions, reduces heat pollution on the environment, the other partySurface, due to the production of sanitary hot water, free of charge on boilers, heaters and other traditional heating equipment, at the same time, excessive dependence on liquid refrigerant further cooling effect, improves the chiller energy efficiency ratio, improved the unit operating conditions, and increased operating life of the unit, the overall reduce overall operational costs. Therefore, the heat recovery technology is of great practical significance and high social benefits, with energy-saving, environmental protection and conservation of the features of running costs, to a certain extent reflects the country is in the process of creating a "society" of overall objectives, should in the industry and the whole of society to promote. Reference 1) of the refrigeration technology and its applications (1st Edition), editor-in-Chief of Yen-Chi Sen timber industrial associate editor shenjiang stone China cultural China construction industry press 2) the small refrigeration appliance design guidelines "(1st Edition), editor-in-Chief of Wu industry mechanical industry press editorial: Feng Rui-Kit