Experimental Study On Multi-Source Heat Pipe Compound Vapor Compression Heating Unit

With the increasing of the scarcity of energy resources and building energy consumption in recent years,the application of solar energy,shallow soil thermal energy,air energy and other renewable energy sources in the field of heating and air conditioning has become the frontier and hot spot of the research.According to statistics,the building energy consumption has exceeded 25%of the total energy consumption of society.Heating and air conditioning accounted for the largest proportion of building energy consumption due to the large area and long heating period in cold regions of our country,which is the top priority of building energy saving and emission reduction.Heat pump technology with its energy saving,environmental protection and other advantages in heating and air conditioning system has been widely used.However,there are many problems in the application of a single heat source heat pump system in the cold regions,such as the large area and high cost of the heat collector of solar heat pump,the soil thermal imbalance and recharge difficulties of ground source heat pump,the poor performance and outdoor heat exchanger frosting of air source heat pump and so on.In order to give full play to the advantages of three kinds of heat pump technology and learn from each other,the core part of the multi heat source coupled heat pump heating and air conditioning system which is two-stage compression composite separated type heat pipe heating unit are studied through experiments based on the propose of multi heat source coupled heat pump system by previous research group.This paper mainly conducts the research from the following aspects:Firstly,the theoretical calculation of the double stage compression heat pump cycle system is carried out based on the theory of two-stage compression heat pump cycle.The two-stage compression cycle of double heat source heat pump system which is suitable for low temperature is analyzed and optimized.The experimental system scheme is determined.Secondly,the main components of the unit are designed and calculated with R22 as refrigerant,mainly including heat collector/evaporator,water cooled condenser,compressor,throttle valve,economizer.The design process should ensure that the heating condition of separate type heat pipe and two stage compression system can play the best performance and ensure the reliability and energy efficiency of the unit.Finally,according to the design results of the unit,the various components of the unit are selected.The performance testing platform of dual source two-stage compression composite separated type heat pipe heating unit is set up.The performance of the heat pipe condition is studied in different conditions,including solar radiation intensity,outdoor ambient temperature,cooling water inlet temperature,cooling water flow rate,the blowing rate of outdoor air blower.The performance of the dual-source vapor compression heating condition is studied in different conditions,including solar radiation intensity,outdoor ambient temperature,cooling water inlet temperature,cooling water flow rate,the blowing rate of outdoor air blower.Through the analysis of experimental results it shows that the heating condition of separate type heat pipe and two stage compression system of the unit have good heating performance.In this paper,the effects of different internal and external factors on the performance of the unit are fully considered.The experimental results show that the two-stage compression composite separated type heat pipe heating unit has good feasibility for building heating in cold regions.The research of this paper can provide theoretical basis and technical support for the application of multi heat source coupled heat pump heating and air conditioning system in cold regions in the future.