Research on a phase-change storage heating system of a solar-ground source heat pump based on low current

doi:10.19799/j.cnki.2095-4239.2023.0446

Abstract

Abstract:

To alleviate the typical high-energy consumption associated with greenhouse heating in winter in northern China, in this study, a greenhouse in Hebei Province is considered as the research object. Based on the existing solar-coupled ground source heat pump heating system in the greenhouse, TRNSYS software is employed to simulate a model of a solar-ground source heat pump phase-change storage heating system driven by low current. In addition, the operation of the system driven by low power is investigated, and the effect of different heat-storage temperatures of the phase-change heat-storage tank on the heating performance of the system is analyzed. Furthermore, the soil heat imbalance problem of the ground source heat pump in the heating of an agricultural greenhouse is investigated, and the economy of the solar-ground source heat pump phase-change heat-storage-heating system is analyzed. The results reveal that the optimum heat-storage temperature of the phase-change heat-storage tank is 44.4 ℃, and the utilization rate of off-peak electricity reaches greater than 98% during the entire heating season. Under the condition that the system has been running for 10 years, the buriedpipe of the solar-coupled ground source heat pump heating system stores 47232 kWh less heat than that stored by the buried pipe to the soil, and the solar-coupled ground source heat pump phase-change heat storage-heating system stores 4487 kWh more heat than that stored by the buried pipe to the soil. The solar-ground source heat pump phase-change storage heating system can better maintain the soil-temperature balance. The solar-coupled ground source heat pump heating system costs 76095 CNY for 15 years of operation, while the solar-ground source heat pump phase-change thermal storage heating system costs 35516 CNY for 15 years of operation; the operating cost is reduced by 53% compared to with that of the solar-coupled ground source heat pump heating system. The comprehensive annual cost of the solar-ground source heat pump phase-change storage heating system and the solar-coupled ground source heat pump heating system are 10890 CNY and 11920 CNY, respectively. The comprehensive annual cost is reduced by 8% in comparison with that of the solar-coupled ground source heat pump heating system, and the solar-ground source heat pump phase-change storage heating system provides better economic benefits.

Key words: phase change heat storage, solar energy, cross-season heat storage, TRNSYS

CLC Number:

TU 833

Yalei ZHANG, Haiting CUI, Chen WANG, Haosong CHEN, Chao WANG. Research on a phase-change storage heating system of a solar-ground source heat pump based on low current[J]. Energy Storage Science and Technology, 2023, 12(12): 3789-3798.

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项目	模拟值	实验值^[14,16]	相对误差
热泵供热量/kWh	29745	29601	0.49%
太阳能供热量/kWh	3452	3547	2.67%
系统总供热量/kWh	33643	33149	1.49%
热泵系统耗电量/kWh	9728	9511	2.28%
热泵机组COP	3.43	3.56	3.65%

参数	数值
热泵机组供热量/kWh	26397
太阳能累计集热量/kWh	3868
相变储热罐累计蓄热量/kWh	18889
相变储热罐累计放热量/kWh	18887
热泵机组能耗/kWh	9043
热泵机组COP	2.95

供暖类型	太阳能耦合地源热泵供暖系统	太阳能-地源热泵相变蓄热供暖系统
太阳能累计集热量/kWh	201913	207944
太阳能直供热量/kWh	39224	34254
地埋管向土壤蓄热量/kWh	162689	173690
地埋管向土壤取热/kWh	209921	169207
系统总供热量/kWh	336249	293651
热泵机组供热量/kWh	296982	259397

供暖类型	太阳能耦合地源热泵供暖系统	太阳能-地源热泵相变蓄热供暖系统
热泵供热量/kWh	446064	386706
热泵机组能耗/kWh	146336	131541
太阳能直供/kWh	58246	51410

费用名称	供暖系统初始投资/元
合计	77000
地源热泵	21000
太阳能集热器总费用	14000
水箱费用	2500
水泵总费用	1500
地埋管井群总费用	17500
风机盘管	6000
相变储热罐及相变材料	14500