Abstract
Heat pipe heat exchangers (HPHEXs) are widely used in various industries. In this paper, a novel model of a liquid–liquid heat pipe heat exchanger in a countercurrent manner is established by considering the evaporation and condensation thermal resistances inside the heat pipes (HPs). The discrete method is added to the HPHEX model to determine the thermal resistances of the HPs and the temperature change trend of the heat transfer fluid in the HPHEX. The established model is verified by the HPHEX structure and experimental data in the existing literature and demonstrates numerical results that agree with the experimental data to within a 5% error. With the current model, the investigation compares the effectiveness and minimum vapor temperature of the HPHEX with three types of HP diameters, different mass flow rates, and different H* values. For HPs with a diameter of 36 mm, the effectiveness of each is improved by about 0.018 to 0.029 compared to HPs with a diameter of 28 mm. The results show that the current model can predict the temperature change trend of the HPHEX well; in addition, the effects of different structures on the effectiveness and minimum vapor temperature are obtained, which improve the performance of the HPHEX.
Highlights
As the world’s energy forms become increasingly tense, green energy and low carbon emissions have become the mainstream
The temperature difference between the hot and cold fluid can be calculated by the vapor temperature; the vapor temperature of the heat pipes (HPs) is an important factor that determines the thermal resistance in the HP
The thermal resistance outside the HP is dependent on the convection heat transfer coefficient, which is determined by the qualitative temperature and Reynolds number at the cold side and hot side
Summary
As the world’s energy forms become increasingly tense, green energy and low carbon emissions have become the mainstream. A novel mathematical model, including the thermal resistances of evaporation and condensation inside HP, is to be proposed for predicting the heat transfer performance of liquid–liquid HPHEX, and the numerical solution results are to be presented. The temperature profiles of hot side and cold side of HPHEX and the trend of temperature variation of the working fluid inside HPs are to be predicted. Because of the coupling relationship between vapor temperature and the working pressure of HPs, which is of great significance to the optimization of the design, it is necessary to systematically study the shape and temperature variation law of HPs. H* of the HPs, and the effect on the thermal performance is obtained. Because of the coupling relationship between vapor temperature and the working pressure of HPs, which is of great significance to the optimization of the design, it is necessary to systematically of 19 study the shape and temperature variation law of HPs
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