The Exergy Cost Analysis Method Research Of Ground Source Heat Pump System

The ground source heat pump (GSHP) is a sort of building heating and coolingsystems that using energy efficiently. It has a very fast development recently anddraws a lot of attention, especially the energy and environmental problems isbecoming more and more serious. And the GSHP is seen as one of the heat pumpsystem that has most develop future. But, in order to use the shallow soil as the heatsource, there must be a out-door ground heat exchanger that leads to a higher initialcost. Therefore, the use of ground source heat pump is restricted heavily, and itseconomy is also questioned. In order to analyze the economy of the GSHP on essenceof energy, the exergy analysis method is used in this paper. And the air source heatpump system is elected as comparative object.In the paper, the exergy analysis model of the GSHP system and air source heatpump system is established based on exergy concept of thermodynamics andeconomics knowledge. The energy analysis model also is given in the paper in order tocompare whit the exergy analysis model. The design calculation method of theout-door ground heat exchanger system and the energy consume calculating method ofthe two heat pump systems is introduced also. In order to analyze the effect of initialcost of out-door ground heat exchanger and life cycle on the economy of GSHPsystem, the sensitivity analysis method is used and the caculation model is alsoestablished in the paper.One air-conditioning system of a building object in Changsha is chose as theanalysis example in the paper. The ground source heat pump system and the air sourceheat pump system are calculated by using exergy cost analysis model and energy costanalysis method and sensitivity analysis method. The unit cooling exergy cost, the unitheating exergy cost, the unit cooling capacity cost and the unit cooling capacity costof air source heat pump are15.1%,7.3%,16.7%and7.5%higher than that of theGSHP system, respectively. So the economy of the GSHP system is better than the airsource heat pump system. The unit cooling exergy cost of the GSHP system and the airsource heat pump system is1.49times and1.60times of the heating exergy cost ofthemselves. So the exergy analysis method can reflect the quality of energy, and weshould mainly pay attention to the efficiency of cooling model of the heat pumpsystem. But the unit cooling capacity cost of the GSHP system and the air source heatpump system is0.79times and0.86times than the heating capacity cost of themselves.So the energy cost analysis can not reflect the value of cooling capacity and gives a wrong way for system energy saving. According the conclusion of sensitivity analysis,it can be found that when the initial cost of GSHP system is1.84times of that of airsource heat pump there will be no advantage in exergy cost for GSHP system. If thelife cycle is biger, the effect of it on energy cost and exergy cost is smaller. And withthe change of life cycle, the proportion relation between unit cooling exergy cost andunit heating exergy cost keeps invariant. There is the same rule between unit coolingcapacity cost and unit heating capacity cost.