上海理工大学学报  2022, Vol. 44 Issue (4): 381-387 PDF

Matching of heating water tank and thermal storage tank in photovoltaic thermal-heat pump system
QU Minglu, YAN Nannan, WANG Haiyang, LU Mingqi
School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China
Abstract: To study the problem of size matching of the heating tank and the thermal storage tank in the photovoltaic thermal-heat pump system, a simulation model of the photovoltaic and thermal-heat pump system was established by using TRNSYS software. The model was tested using the measured data, and the findings revealed that the errors were within reasonable bounds, indicating that the simulation model was accurate and dependable. Thermal storage tanks with the sizes of 30, 60, 90 L/m2 were selected to match the heating water tanks with different capacities of 100, 200, 300 L, respectively, and an annual operating performance simulation of the system model was conducted using the system model. To evaluate the system, the annual exergy loss was chosen as the evaluation index. Simulation results show that the annual exergy loss of the system is the smallest when the capacity of the storage tank is 60 L/m2 for all the three different capacities of the heating water tank. As a result, the thermal storage tank with a size of 60 L/m2 is advised to match each capacity of the heating water tank.
Key words: solar energy     photovoltaic thermal     heat pump     TRNSYS software     exergy loss     performance simulation

1 实验系统

 图 1 光伏光热-热泵系统图 Fig. 1 Photovoltaic thermal-heat pump system diagram
2 系统综合效率分析

 $E_{\text {l}}=\left(P_{{\rm{W}}}+P_{{\rm{H}}}+E_{\text {s}}\right)-\left(P_{0}+E_{{\rm{X}}, {\rm{C}}}\right)$ (1)

 $E_{{\rm{X}}}=Q_{{\rm{H}}}\left(1-\frac{T_{0}}{T}\right)$ (2)

 $E_{{\rm{C}}}=Q_{{\rm{e}}}\left(1-\frac{T_{0}}{T_{{\rm{c}}}}\right)$ (3)

 $E_{\text {s}}=Q_{\text {s}}\left[1-\frac{4}{3} \frac{T_{0}}{T_{{\rm{s}}}}+\frac{1}{3}\left(\frac{T_{0}}{T_{{\rm{s}}}}\right)^{4}\right]$ (4)

PV/T组件光电转换效率 $n_{\rm{P}}$ 为光电输出功率与太阳有效热能的比值，热泵的制热量 $Q_{\rm{H}}$ 为供热侧进出水管中循环水得热量。

 $n_{{\rm{P}}}=W_{{\rm{P}}} / Q_{\text {s}}$ (5)

 $Q_{{\rm{H}}}=m_{{\rm{L}}} c\left(T_{{\rm{out}}}-T_{{\rm{in}}}\right)$ (6)

 $C O P=Q_{{\rm{H}}} /W$ (7)

3 系统性能模拟与结果分析

 图 2 光伏光热−热泵系统仿真模型 Fig. 2 Simulation model of the photovoltaic thermal-heat pump system
3.1 系统模拟验证

 图 3 实验的气象参数 Fig. 3 Meteorological parameters of the experiment

 图 4 两水箱温度的实验与模拟数据对比 Fig. 4 Comparison of experimental and simulated data for the temperature of two water tanks

 图 5 发电量的实验与模拟数据对比 Fig. 5 Comparison of experimental and simulated data of power generation
3.2 模拟工况

3.3 模拟结果分析

 图 6 不同容量时系统电效率逐月变化情况 Fig. 6 Monthly change in electrical efficiency of the system under different capacities

 图 7 不同容量时热泵机组逐月运行能耗 Fig. 7 Monthly operating energy consumption of heat pump units under different capacities

 图 8 不同容量时系统全年COP变化情况 Fig. 8 Annual COP change of the system under different capacities

4 结　论

a. 水箱容量越大，系统全年的平均电效率越高，热泵机组的年平均COP越大，但是，在直供模式下供热水箱达到设定温度的时间越长。

b. 以全年㶲损作为系统运行性能评价指标，通过计算不同容量供热水箱下系统的全年㶲损可知，100，200，300 L供热水箱容量下最匹配的蓄热水箱大小均为60 L/m2，此时系统运行性能更佳。

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