Low-temperature Heat Recovery Application Research Of Heat Pipe And Heat Pump

With the sustained rapid economic growth, the living standards of people are rising continuously. As a result, the popularity of air conditioning is enhancing year by year. At the same time, its energy consumption is also growing. There is a large deal of waste heat in the operation of the air conditioning system. Therefore, how to reduce air conditioning energy consumption has drawn increasing attention from people. To adopt a heat recovery installation in the air conditioning system can recover the cold heat from ventilation effectively. The cold heat can be used to do a certain degree of pretreatment to outdoor fresh air. Thereby, without increasing of energy consumption, the indoor air ratio in increased, the indoor air quality is improved, and the energy required to heat fresh air is also reduced. Consequently, the dual purpose of energy saving and environmental protection can be achieved through reducing the load of unit and improving the economical property of the system.As there are frequent freeze damage accidents when fresh air unit operates in cold regions'winter, the indoor air quality cannot be guaranteed. To solve this problem, this paper puts forward the suggestion that to apply low-temperature heat pipe heat pump heat recovery units to the air-conditioned fresh air unit. So the fresh air can be preheated with full use of building's ventilation. Thereby, the temperature of fresh air is enhanced and running time of the fresh air unit in the heating period is effectively extended. Consequently, the freeze damage problem of heat pump unit and fresh air unit in winter of the cold regions is solved. At the same time, this can ensure good indoor air quality. This paper first analyzes applications of the heat recovery of heat pipe heat pump at home and abroad, and then discusses the feasibility of low-temperature heat pipe heat pump heat recovery units theoretically. Also, theoretical and experimental researches are done to this heat recovery unit. Theoretically, the constitution, working principle and air treatment process of the unit are discussed. The design of the heat recovery unit is also given. Experimentally, the laboratory bench of low-temperature heat pipe heat pump heat recovery unit is built. Theoretical analysis and calculation is also made based on the experimental results.Through the measurement studies of the unit, the running characteristics and results of the system are gained tentatively. The experimental results show that: the system operates stably in running period, the temperature of fresh air supplied increases by 33℃averagely, thus the fresh air preheat requirement is met; the average heat recovery efficiency is 83%, up to 92%, so heat recovery effect is remarked; power consumption is greatly reduced, with an average saving of 22% of operating costs; the analysis results of the economical and safe property of the system shows that the payback period of the system is 2.73 years, so the economical property is good; the system has solved the frost crack problem of fresh air in cold regions, and through supplying fresh air continuously to the room, the need for fresh air of those who are inside the building is ensured, indoor environment is improved, thus this system is of good safety.