Effects of mixed working fluids on the performance of a combined power and ejector refrigeration cycle

doi:10.3969/j.issn.2097-0706.2023.04.004

Abstract

Abstract:

A combined power and ejector refrigeration cycle （CPERC） can simultaneously generate power and cold by coupling a power cycle with a ejector refrigeration cycle. CPERCs，driven by medium and low-temperature thermal energy，are applicable in renewable energy utilization，waste heat recovery and other fields. Different from the cycle with a single function，a CPERC needs to ensure the good temperature match between the heat source and the cycle and that between the refrigerant and the cycle simultaneously.For the power cycle，the organic flash cycle can achieve a good temperature match between the temperature-swing heat source and the cycle.For the refrigeration cycle，zeotropic working fluid can achieve a good temperature match between the cycle and the refrigerant.Therefore，the CPERC taking the organic flash cycle and zeotropic working fluid can achieve the temperature matches above simultaneously.By establishing a mathematical model， the effect of the R600a/R601a zeotropic mixture on the performance of the CPERC is studied. The results show that when the mass fraction of R600a is 0.3，the exergy efficiency of the CPERC peaks at 37.38%，which is 4.20% higher than that of the CPERC taking pure R600a and 6.30% higher than that of the CPERC taking pure R601a as its working fluid.

Key words: combined power and cooling cycle, organic flash cycle, ejector, mixed working fluid, refrigeration

CLC Number:

TK114：TK123

ZHAO Dongpeng, ZHAO Li, DENG Shuai, ZHAO Ruikai, XU Weicong. Effects of mixed working fluids on the performance of a combined power and ejector refrigeration cycle[J]. Integrated Intelligent Energy, 2023, 45(4): 26-34.

Figures/Tables 9

Fig.1

Fig.2

Table 1

Control equation for each component

部件名称	能量守恒方程及其他控制方程
工质泵	$P i n = q m, p h 2 - h 1, η p u m p = h 2, s - h 1 / h 2 - h 1$ 式中： $q m, p$ 为动力循环的工质质量流量；η_pump为工质泵的等熵效率；h_2,s为等熵条件下工质泵出口处工质的比焓
内部换热器	$Q i h e = q m, p h 3 - h 2 = q m, t u r h 6 - h 7$ 式中：Q_ihe为内部换热器的换热功率； $q m, t u r$ 为流经膨胀机的工质质量流量
加热器	$Q i n = q m, g w h g w, i n - h g w, o u t = q m, p h 4 - h 3$ 式中：Q_in为循环在加热器中的吸热功率； $q m, g w$ 为地热水的质量流量；h_gw,in为加热器入口处地热水的比焓；h_gw,out为加热器出口处地热水的比焓
闪蒸分离器	$h 4 = h 4', q m, t u r = q m, p x 4', q m, e j e = q m, p 1 - x 4'$ 式中： $q m, e j e$ 为喷射器一次流体的质量流量； $x 4'$ 为闪蒸后工质的干度
膨胀机	$P o u t = q m, t u r h 5 - h 6, η t u r = h 5 - h 6 / h 5 - h 6, s$ 式中：η_tur为膨胀机的等熵效率；h_6,s为等熵条件下膨胀机出口处工质的比焓
节流阀	$h 9 = h 1$
蒸发器	$Q c = q m, f w h f w, i n - h f w, o u t = q m, c h 10 - h 9$ 式中： $q m, f w$ 为冷冻水的质量流量；h_fw,in为蒸发器入口处冷冻水的比焓；h_fw,out为蒸发器出口处冷冻水的比焓； $q m, c$ 为制冷子循环的工质质量流量
喷射器	$μ = q m, c / q m, e j e$
混合器	$q m, c + q m, e j e h 11 + q m, t u r h 7 = q m, c + q m, p h 12$
冷凝器	$Q o u t = q m, c w h c w, o u t - h c w, i n = q m, c + q m, p h 12 - h 1$ 式中：Q_out为循环在冷凝器中的放热功率； $q m, c w$ 为冷却水的质量流量；h_cw,in为冷凝器入口处冷却水的比焓；h_cw,out为冷凝器出口处冷却水的比焓

Table 1

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