| Heat pump hot water system compared with many other hot water supply methods,its energy-saving,efficient and environmentally friendly advantages make it increasingly prominent in the field of centralized supply of building hot water,and the application of heat pump system in hot summer and warm winter areas has superior natural climatic conditions and geological conditions,Taking the air source heat pump coupled ground source heat pump hot water system of a health school in Nanning as the research object,combined with the climatic conditions in the hot summer and warm winter areas,the experimental research,theoretical analysis and simulation calculation are carried out,and the main research contents and achievements are as follows:(1)The heating demand and equipment matching of the hot water Project are analyzed,including the heating capacity of the heat pump unit,the heat transfer capacity of the buried pipe system and the calculation of the water supply demand flow,and the applicability and practicability of the hot water system are evaluated.The results show that the hot water system can meet the needs of building hot water.(2)Through the Experimental research and analysis of hot water system at different ambient temperature,the user water and system operation Law are summarized.With the decrease of ambient temperature,the operation performance of heat pump unit decreased slightly,when the ambient temperature was 15 ?,the COP and the system COP of the ground source heat pump unit were 3.72 and 3.24 respectively,the COP and the system cop of the air source heat pump unit were 3.1 and 2.83 respectively,and when the ambient temperature was 8 ?,The COP and the system cop of the ground source heat pump unit are 3.43 and 2.96 respectively,the COP and the system COP of the air source heat pump unit are 2.45 and 2.15 respectively,and the influence of the effluent temperature and unit load rate of the condenser on the performance of the 2 platform source heat pump unit is discussed respectively.The energy-saving operation scheme which should give priority to meet the heating capacity of unit 1th is put forward,The improved operation scheme can increase the average COP of the two soil source heat pump units by 0.08,and the heating contribution rate of two heat pump units under different ambient temperatures is analyzed,when the ambient temperature is 15 ?,the heating contribution rate of the ground source heat pump unit is 74%,the air source heat pump unit accounts for 26%,and when the ambient temperature drops to 8 ?,the heating contribution rate of the ground source heat pump unit has reached 82%,and the heating contribution rate of the air source heat pump unit is reduced to 18%.and it is found that the reduction of ambient temperature will make the system more dependent on the ground source heat pump unit.(3)Aiming at the operating characteristics of the system under different seasons,the energy flow analysis model of hot water system is established respectively,and the exergy loss and exergy loss rate and exergy efficiency of hot water system and each equipment under different seasons are calculated.Among them,the total exergy loss of the whole hot water system in winter is 351.3kw,the total exergy loss of the transition season is 356.9kw,The total exergy loss in summer is 215kw,and the exergy efficiency in winter,transition season and Summer are:0.415,0.338 and 0.224,Ground-source heat pump units and air source heat pump units are important components of the system to produce the energy loss of the system,in winter,transition season and summer,the ground source heat pump unit's exergy loss rate reached 45.8%,46.7%and 85.2%,respectively,while the air source heat pump unit in the winter and the transition season of the exergy rate of loss of 41%and 41.6%,respectively,(The system is to simplify the control,the air source heat pump unit does not run in summer),so reducing the energy loss of the heat pump unit is the key to improve the energy conversion efficiency of the system.The exergy efficiency of each subsystem is sorted from large to small:transmission and distribution Pipeline>system pump>Ground source Heat pump Unit>Air source Heat pump Unit,Among them,the exergy efficiency of air source heat pump unit in winter is 19.6%lower than the ground source heat pump,the transition season is 36.3%lower,so the ground source heat pump unit has higher energy conversion efficiency and better thermal perfection than the air source heat pump.By comparing with the analysis and comparison of traditional fossil energy hot water equipment in low temperature environment,it is found that the exergy efficiency of soil source heat pump unit can reach 2.7 times the average utilization rate of traditional hot water equipment,while the efficiency of air source heat pump unit can reach 2.1 times that of traditional hot water equipment,and the advantages of energy saving and efficiency of hot water pump unit are more prominent.(4)In view of the problem of soil heat imbalance in the operation of soil source heat pump system,the TRNSYS software is used to simulate the ground source heat pump system studied in this paper,and the results show that the average annual variation of soil temperature is small and stable under the condition of annual hot water supply operation(except school winter and summer vacation),The system design is reasonable and the system runs stably. |
PDF Full Text Request