| Hot summer and warm winter areas in China,cooling in summer is an indispensable link,and the common air-conditioning plays an important role in this link,but when the air-conditioning works in summer,amount of condensing heat is let out of the room,which wastes the energy and also causes the thermal pollution of the environment that has worsened the "heat island effect" of the city.Domestic hot water are absolutely necessary for families,but high energy consumption is always a defect for the conventional equipment of hot-water.Comparing with other areas,hot summer and warm winter areas in southern China have some characteristics,such as adequate rainfall,long-time summer,high average temperature of shallow soil,etc.According to these characteristics,some researches are carried out for the heating-cooling combined ground source heat pump system with horizontal ground heat exchanger,and the main conclusions are obtained as follows under this experimental condition:(1)In winter and part of the transition season,the system makes hot-water by the horizontal ground heat exchanger absorbing the heat from the underground soil,and hot-water are produced by using the condensing heat from the cooling of the air-conditioning in canteen in summer.Under the condition of horizontal ground heat exchanger,the system can keep a good performance throughout the year,the COP of unit and system are the lowest in January,which are 4.61 and 4.03,,the highest in November,4.88 and 4.27,respectively.Meanwhile,the operation performance do not drop with years of use under the condition of horizontal ground heat exchanger,the average COP of unit and system in a year can keep 4.75 and 4.18,respectively.(2)Under the condition of heating-cooling combined,the operation performance of system is directly related to the high low of the environment temperature and the number of people,which gets the best at 12'clock.During the period of heating-cooling combined,the system can always keep a good performance,and the average comprehensive COP of unit and system are 7.07 and 6.27,respectively.(3)This system only absorbs the heat from the underground soil and do not discharge the heat throughout the year,it is unreasonable for the design from the theory,but the problem of heat balance got a good solution by using the advantage of the high environment temperature and strong solar radiation in hot summer and warm winter,the own characteristics of horizontal ground heat exchanger and the reasonable design of system.The average temperature of chilled water are different in different month,but it doesn't generate larger variety in the same month of different years,which shows that the underground temperature field didn't change with the change of year.(4)Under 2.5m for the depth of pipe trench,the average of heat exchange quantity per pipe length and pipe trench in a year with the pipe arrangement of three layers are 18.2W/m and 109.W/m,respectively,the pipe arrangement of four layers are 15.2W/m and 121.6W/m,under the case of that the latter of heat exchange quantity per pipe trench increased by 2.7%comparing with the former,the heat exchange quantity per pipe trench increased by 11.4%,which can reduce 11.4%of pipe trench length and the whole occupied area.So the horizontal ground heat exchanger with the pipe arrangement of four layers will have more application advantages compared with the horizontal ground heat exchanger with the pipe arrangement of three layers.(5)The investment cost per heat exchange quantity for horizontal ground heat exchanger is 53.3%lower than that of the vertical ground heat exchanger,Which means that the investment cost of the horizontal ground heat exchanger has very big advantage.The heat exchange quantity per pipe length for the pipe arrangement of three layers with horizontal ground heat exchanger are 18.2W/m that is 27%lower than 25.0W/m of the vertical ground heat exchanger,which means that the vertical ground heat exchanger has a good performance at heat exchange quantity per pipe length compared with the horizontal ground heat exchanger.Meanwhile,the occupied area of the horizontal ground heat exchanger is 7 times more than the vertical ground heat exchanger's when both have a similar value on the whole heat exchange quantity.(6)The heating-cooling combined ground source heat pump system with horizontal ground heat exchanger needs different power consumption make a ton of hot-water in different season and month,the power consumption of hot-water per ton is the largest in January,which is 10.7kwh/t,it is the lowest in June,which is 7.5kwh/h,the average power consumption of hot-water per ton in the whole year is 9.0kwh/h,the cooling capacity provided to the canteen is almost free of charge in summer.The operation cost of this system in the whole year is separately 74.2%?72.2%and 50.9%lower than of the electric boiler plus central air conditioning system,boiler plus the central air conditioning system or air source heat pump plus the central air conditioning system,which this has a big advantage compared with other conventional systems in energy conservation. |
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