Research On The System Coupled With Combined Cooling, Heating And Power System Based On Natural Gas And Ground Source Heat Pump System

At present, building energy-saving problems have not been allowed to ignore. Buildingenergy-saving is generally carried out by the following three ways: building ontology, buildingenergy-efficiency equipment and building energy sources. And the latter two play a key role inthe building energy-saving running, namely “open source” and “throttling”. In the “opensource”, the combined cooling, heating and power system based on natural gas (NG-CCHP)and ground source heat pump as the representative of distributed energy system is used widelyand efficient energy supply system. After a literature review, there are some problems in theapplication process of the two types systems, namely which develop almost in parallel and cannot achieve the cross amalgamation. Even if the coupling between the two types system isresearched by the part researcher in the same field, but which still is the simple sum of the twoand can not form the complementary advantages of the systems and achieve the depthintegration based on the energy cascade utilization principle.Therefore, a new distributed energy system coupled with NG-CCHP and ground sourceheat pump (GSHP) is proposed, in which the principle of the energy grade promotion andenergy cascade utilization is integrated, which makes the two systems become an integrationsystem, which eliminates the simple superposition to form a new trigeneration system coupledwith multi-energy.To further interpret the energy-saving mechanism and performance characteristics of thecoupled system, a typical composite energy supply system is given. The traditional NG-CCHPand the “parallel” system coupled with NG-CCHP and GSHP are selected as the referenceobject. Low-grade waste heat utilization efficiencyη1and relative energy-saving rateη2isused as the performance evaluation criteria. The influence characteristic of the coupling criticaloperating parameters on the performance of the integrated energy supply system is alsoanalyzed. The following conclusions can be given through the research and analysis.(1) The low-grade waste heat utilization efficiency of the integrated energy supply systemis117%, in which the energy efficiency of GSHP increases by95.9%compared with theconventional one. The low-grade waste heat utilization efficiency of “parallel” energy supplysystem is104%. So when the reference system is “parallel” energy supply system andNG-CCHP, the relative energy-saving rate of low-grade waste heat utilization of the integratedenergy supply system is12.5%and17%, respectively. When the reference system isNG-CCHP, the relative energy-saving rate of the integrated energy supply system is4.0%.(2) When the building energy demand is met, the primary energy consumption of the integrated system reduces by29.1Nm3/h compared with NG-CCHP. The power demand of theintegrated system reduces by29.6kW/h compared with the “parallel” energy supply system.And the grade of power is much higher than low-grade waste heat (180℃-120℃).(3) In the integrated system which is coupled with NG-CCHP and GSHP by the changingthe utilization way of waste heat of NG-CCHP, when the goal is to reduce the drilling area ofGSHP, the waste heating of NG-CCHP can be coupled with the inlet at ground source side ofunits. When the goal is to promote the low-grade waste heat utilization efficiency, the wasteheating of NG-CCHP can be coupled with the outlet at demand side of units.