Study on the cycle performance of salt solution-storage-based heat pump

doi:10.11949/0438-1157.20221620

Abstract

Abstract:

In order to solve the problem of electricity demand peak and valley in heating period, a solution-based energy-stored heat pump (SEHP) is proposed, which is composed of compression heat pump subsystem and salt solution subsystem with energy storage and release to realize thermal storage and thermal grade improvement. The multi-layer liquid storage units are used to optimize the design of salt solution storage tank to improve the energy storage density. Based on the thermodynamic model of the new cycle, the effect of key operating parameters on the performance of SEHP are studied, and its economy makes comparisons with that of the air-source energy-stored heat pump (AEHP) and the air-source heat pump (ASHP). The results show that the comprehensive heating coefficient of performance (CCOP) of the new cycle is lower than that of AEHP and ASHP, but its energy storage density (ESD) and economy are better than those of the two conventional heat pumps. At 300 kW heating load, although CCOP of SEHP is 4.76% lower than that of AEHP, ESD of SEHP is 2.2 times higher than that of AEHP, while the annual cost of AEHP is 1.46% and 29.00% lower than that of AEHP and ASHP respectively.

Key words: thermodynamics, salt solution, energy storage, heat pump, coefficient of performance, economy

摘要：

为解决供热采暖期的电力峰谷问题，提出了盐溶液蓄能型热泵循环，由压缩热泵子系统与盐溶液储释能子系统构成复叠循环实现热能储存与品位提升，利用多层储液思想设计盐溶液储罐结构提升蓄能密度。在建立新循环热力学数学模型的基础上，研究关键运行参数对新循环的性能影响，并评估比较了新循环、传统空气源蓄能热泵和空气源热泵的经济性。研究结果表明：新循环综合制热性能系数低于传统空气源蓄能热泵及空气源热泵，但其蓄能密度和经济性均优于传统两种热泵循环。在300 kW供热量设计负荷下，新循环综合制热性能系数较传统空气源蓄能热泵降低4.76%，但新循环蓄能密度是传统空气源蓄能热泵的2.2倍，而新循环费用年值较传统空气源热泵及空气源蓄能热泵分别降低1.46%和29.00%。

关键词: 热力学, 盐溶液, 蓄能, 热泵, 性能系数, 经济性

CLC Number:

TK 123

Minghui CHANG, Lin WANG, Jiajia YUAN, Yifei CAO. Study on the cycle performance of salt solution-storage-based heat pump[J]. CIESC Journal, 2023, 74(S1): 329-337.

常明慧, 王林, 苑佳佳, 曹艺飞. 盐溶液蓄能型热泵循环特性研究[J]. 化工学报, 2023, 74(S1): 329-337.

Figures/Tables 12

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状态点	蓄能阶段参数	数值	状态点	释能阶段参数	数值
1	蒸发温度/℃	22.3	4	蒸发温度/℃	-15
1	蒸发压力/kPa	612.8	4	蒸发压力/kPa	164.1
5	蒸发冷凝器入口焓/(kJ/kg)	145.7	4	风冷换热器入口焓/(kJ/kg)	101.2
1	蒸发冷凝器出口焓/(kJ/kg)	259.6	3	风冷换热器出口焓/(kJ/kg)	238.3
3	冷凝温度/℃	65	1	冷凝温度/℃	36.7
3	冷凝压力/kPa	1889.3	1	冷凝压力/kPa	928.3
2	溶液解吸器入口焓/(kJ/kg)	286.9	1	蒸发冷凝器入口焓/(kJ/kg)	283.3
3	溶液解吸器出口焓/(kJ/kg)	145.7	5	蒸发冷凝器出口焓/(kJ/kg)	101.2
5	制冷剂质量流量/(kg/s)	2.74	5	制冷剂质量流量/(kg/s)	1.68
—	蒸发冷凝器负荷/kW	312.1	—	蒸发冷凝器负荷/kW	305.1
—	溶液解吸器负荷/kW	387.1	—	风冷换热器负荷/kW	229.8
—	风冷换热器/kW	47.0	—	压缩机功率/kW	75.3
—	压缩机功率/kW	75.0	8′	蒸发温度/℃	31.7
10	浓溶液焓/(kJ/kg)	135.1	8′	蒸发压力/kPa	4.67
6	溶液热交换器稀溶液出口温度/℃	54	8′	水蒸气焓/(kJ/kg)	2558.5
6	溶液热交换器稀溶液出口焓/(kJ/kg)	112.8	9	溶液热交换器浓溶液出口温度/℃	33
6′	水蒸气压力/kPa	3.62	9	溶液热交换器浓溶液出口焓/(kJ/kg)	108.5
6′	过热水蒸气焓/(kJ/kg)	2613.9	6	稀溶液焓值/(kJ/kg)	137.0
8	组分水焓/(kJ/kg)	114.3	6	稀溶液质量流量/(kg/s)	1.37
—	溶液发生热/kW	341.1	6	溶液热交换器换热量/kW	33.2
—	组分水质量流量/(kg/s)	0.125	—	盐溶液储罐容积/(m³/h)	3.27
—	组分水储罐容积/(m³/h)	0.45	—	溶液冷却器负荷/kW	300
—	泵功率/kW	0.42	—	泵功率/kW	0.39
—	CCOP	2.0	—	ESD/(kWh/m³)	80.65

状态点	蓄能阶段参数	数值	状态点	释能阶段参数	数值
1	蒸发温度/℃	22.3	4	蒸发温度/℃	-15
1	蒸发压力/kPa	612.8	4	蒸发压力/kPa	164.1
5	蒸发冷凝器入口焓/(kJ/kg)	145.7	4	风冷换热器入口焓/(kJ/kg)	101.2
1	蒸发冷凝器出口焓/(kJ/kg)	259.6	3	风冷换热器出口焓/(kJ/kg)	238.3
3	冷凝温度/℃	65	1	冷凝温度/℃	36.7
3	冷凝压力/kPa	1889.3	1	冷凝压力/kPa	928.3
2	溶液解吸器入口焓/(kJ/kg)	286.9	1	蒸发冷凝器入口焓/(kJ/kg)	283.3
3	溶液解吸器出口焓/(kJ/kg)	145.7	5	蒸发冷凝器出口焓/(kJ/kg)	101.2
5	制冷剂质量流量/(kg/s)	2.74	5	制冷剂质量流量/(kg/s)	1.68
—	蒸发冷凝器负荷/kW	312.1	—	蒸发冷凝器负荷/kW	305.1
—	溶液解吸器负荷/kW	387.1	—	风冷换热器负荷/kW	229.8
—	风冷换热器/kW	47.0	—	压缩机功率/kW	75.3
—	压缩机功率/kW	75.0	8′	蒸发温度/℃	31.7
10	浓溶液焓/(kJ/kg)	135.1	8′	蒸发压力/kPa	4.67
6	溶液热交换器稀溶液出口温度/℃	54	8′	水蒸气焓/(kJ/kg)	2558.5
6	溶液热交换器稀溶液出口焓/(kJ/kg)	112.8	9	溶液热交换器浓溶液出口温度/℃	33
6′	水蒸气压力/kPa	3.62	9	溶液热交换器浓溶液出口焓/(kJ/kg)	108.5
6′	过热水蒸气焓/(kJ/kg)	2613.9	6	稀溶液焓值/(kJ/kg)	137.0
8	组分水焓/(kJ/kg)	114.3	6	稀溶液质量流量/(kg/s)	1.37
—	溶液发生热/kW	341.1	6	溶液热交换器换热量/kW	33.2
—	组分水质量流量/(kg/s)	0.125	—	盐溶液储罐容积/(m³/h)	3.27
—	组分水储罐容积/(m³/h)	0.45	—	溶液冷却器负荷/kW	300
—	泵功率/kW	0.42	—	泵功率/kW	0.39
—	CCOP	2.0	—	ESD/(kWh/m³)	80.65

系统		容量	台数	初投资费用/万元		运行费用/(万元/a)
传统ASHP	壳管冷凝器	300	1	4.8	128.7（总费用）	2.880
	翅片蒸发器	170	1	2.9
	压缩机	130	1	118
	热水泵	26	2	0.6
	电子膨胀阀	—	1	0.6
	储液罐	—	1	0.6
	电子自动控制器	—	1	1.2
传统AEHP	壳管冷凝器	300	1	4.8	198.5（总费用）	1.383
	翅片蒸发器	158	1	2.7
	压缩机	142	1	123
	热水泵	26	2	0.6
	蓄能罐	81	2	1.5
	RT65	63.5	1	63.5
	储液罐	—	1	0.6
	电子自动控制器	—	1	1.2
	电子膨胀阀	—	1	0.6
SEHP循环	溶液解吸器	387	1	5	126.5（总费用）	2.875
	蒸发冷凝器	312	1	2.5
	风冷换热器	230	1	1.6
	压缩机	75	1	41
	溶液冷却器	300	1	1.4
	溶液热交换器	33	1	0.5
	组分水泵	0.5	1	0.1
	盐溶液泵	3.3	2	0.2
	热水泵	26	2	0.4
	盐溶液储罐	33	1	0.4
	组分水储罐	4.5	1	0.1
	溴化锂溶液	49.3	1	73
	节流阀	—	1	0.3

系统		容量	台数	初投资费用/万元		运行费用/(万元/a)
传统ASHP	壳管冷凝器	300	1	4.8	128.7（总费用）	2.880
	翅片蒸发器	170	1	2.9
	压缩机	130	1	118
	热水泵	26	2	0.6
	电子膨胀阀	—	1	0.6
	储液罐	—	1	0.6
	电子自动控制器	—	1	1.2
传统AEHP	壳管冷凝器	300	1	4.8	198.5（总费用）	1.383
	翅片蒸发器	158	1	2.7
	压缩机	142	1	123
	热水泵	26	2	0.6
	蓄能罐	81	2	1.5
	RT65	63.5	1	63.5
	储液罐	—	1	0.6
	电子自动控制器	—	1	1.2
	电子膨胀阀	—	1	0.6
SEHP循环	溶液解吸器	387	1	5	126.5（总费用）	2.875
	蒸发冷凝器	312	1	2.5
	风冷换热器	230	1	1.6
	压缩机	75	1	41
	溶液冷却器	300	1	1.4
	溶液热交换器	33	1	0.5
	组分水泵	0.5	1	0.1
	盐溶液泵	3.3	2	0.2
	热水泵	26	2	0.4
	盐溶液储罐	33	1	0.4
	组分水储罐	4.5	1	0.1
	溴化锂溶液	49.3	1	73
	节流阀	—	1	0.3

系统	初投资/万元	运行费用/万元	费用年值 (0~15年)/万元
传统ASHP	128.7	2.880	19.80
传统AEHP	198.5	1.383	27.48
SEHP循环	126.5	2.875	19.51