Operating characteristics and advanced exergy analysis of plate heat exchangers and their thermal system

doi:10.11949/0438-1157.20201516

Abstract

Abstract:

The exergy distribution of different heat exchanger combinations and the heat exchanger in the thermal system were studied, and an advanced exergy analysis model was established to further divide the exergy destruction into unavoidable parts and avoidable parts. The main energy loss in the heat exchanger and thermal system were determined by the calculation of the corresponding exergy destruction and exergy efficiency. It was verified in the organic Rankine cycle (ORC) system text rig, which provided a scientific basis for the optimization of the heat exchangers and thermal system operation. The results showed that different area of heat exchanger had a great impact on the energy efficiency of heat exchanger. And the traditional exergy analysis and the advanced exergy analysis provided different optimization sequences. The advanced exergy analysis showed that the avoidable exergy destruction in evaporator accounted for 41.2%—60.0% while the condenser could avoid 91%—97%. The ORC system had 52.5%—66.3% exergy destruction that could be avoided, which had great potential for optimization. In addition, it was found that unreasonable design of the pipeline would also affect the ORC system performance.

Key words: exergy destruction, exergy efficiency, advanced exergy analysis, organic working fluid, Rankine cycle

摘要：

针对不同换热设备组合之间以及换热设备在系统中的分布情况进行了研究，建立了高级分析模型，将换热设备与系统的损进一步分割成不可避免性部分和可避免性部分，计算相应的损失和效率，确定换热设备与系统中能量损失的主要部位，并在有机朗肯循环（organic Rankine cycle，ORC）系统试验台中进行验证，为换热设备及其热力系统的运行优化提供科学依据。结果表明，不同的换热面积对换热设备的能效有着非常大的影响，同时常规分析和高级分析提出了不同的系统优化次序。高级分析表明，蒸发器可避免损占蒸发器损的41.2%～60.0%，冷凝器可避免损占冷凝器总损最高可达91%～97%，整个ORC系统有52.5%～66.3%的损可以避免，有很大的改造潜力，且发现不合理设计的管道也会影响ORC系统性能。

关键词: 损失, 效率, 高级分析, 有机工质, 朗肯循环

CLC Number:

TK 121

LU Pei, LUO Xianglong, CHEN Jianyong, YANG Zhi, LIANG Yingzong, CHEN Ying. Operating characteristics and advanced exergy analysis of plate heat exchangers and their thermal system[J]. CIESC Journal, 2021, 72(S1): 512-519.

卢沛, 罗向龙, 陈健勇, 杨智, 梁颖宗, 陈颖. 板式换热器及其热力系统的运行特性和高级分析[J]. 化工学报, 2021, 72(S1): 512-519.

Figures/Tables 9

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参数	型号	范围	误差
T	Pt-100（INOR-66RKS）	-200~800℃	±0.1℃
p	压力传感器（PTX5072）	0~3.5 MPa, 0~5 MPa	±0.2%
m_r	Coriolis流量计（OPTIMASS 1330C）	0~400 kg/h	±1.0%
m_v,h	转子流量计（H250-RR-M40）	0.400~4 m³/h	±1.0%
m_v,c	电磁流量计（AXF025G）	>0.060 m³/h	±0.2%
W_exp	测功仪（DW300KC）	—	±0.8%
W_pum	功率监视器（8967B）	—	±1.0%
Q_eva	Q_eva=f(h₁, h₆, m_r)	—	±1.3%
W_net	W_net=f(W_exp, W_pum)	—	±1.0%
η_th	η_th=f(Q_eva, W_exp, W_pum)	—	±2.2%

参数	型号	范围	误差
T	Pt-100（INOR-66RKS）	-200~800℃	±0.1℃
p	压力传感器（PTX5072）	0~3.5 MPa, 0~5 MPa	±0.2%
m_r	Coriolis流量计（OPTIMASS 1330C）	0~400 kg/h	±1.0%
m_v,h	转子流量计（H250-RR-M40）	0.400~4 m³/h	±1.0%
m_v,c	电磁流量计（AXF025G）	>0.060 m³/h	±0.2%
W_exp	测功仪（DW300KC）	—	±0.8%
W_pum	功率监视器（8967B）	—	±1.0%
Q_eva	Q_eva=f(h₁, h₆, m_r)	—	±1.3%
W_net	W_net=f(W_exp, W_pum)	—	±1.0%
η_th	η_th=f(Q_eva, W_exp, W_pum)	—	±2.2%

系统部件	参数	实际循环	不可避免损循环
工质泵pum	η_pum	—	0.95
管路p-e	?p_p-e	0.006 MPa	0.001 MPa
蒸发器eva	?T_eva	1.416℃	0.5℃
管路e-e	?p_e-e	0.062 MPa	0.001 MPa
膨胀机exp	η_exp	0.63	0.95
管路e-c	?p_e-c	0.182 MPa	0.001 MPa
冷凝器con	?T_con	0.745℃	0.5℃
管路c-p	?p_c-p	0.014 MPa	0.001 MPa

系统部件	参数	实际循环	不可避免损循环
工质泵pum	η_pum	—	0.95
管路p-e	?p_p-e	0.006 MPa	0.001 MPa
蒸发器eva	?T_eva	1.416℃	0.5℃
管路e-e	?p_e-e	0.062 MPa	0.001 MPa
膨胀机exp	η_exp	0.63	0.95
管路e-c	?p_e-c	0.182 MPa	0.001 MPa
冷凝器con	?T_con	0.745℃	0.5℃
管路c-p	?p_c-p	0.014 MPa	0.001 MPa

换热器组合	蒸发器		冷凝器
换热器组合	ε_k/%	?_D	ε_k/%	?_D
蒸发器1-冷凝器1	66.78	3.177	39.33	1.264
蒸发器1-冷凝器2	67.24	3.083	38.17	1.224
蒸发器1-冷凝器3	66.37	3.188	36.76	1.258
蒸发器2-冷凝器1	66.37	3.292	38.02	1.290
蒸发器2-冷凝器2	66.03	3.276	36.90	1.257
蒸发器2-冷凝器3	67.55	3.135	35.71	1.304