Numerical study on heat and mass transfer characteristics of the counter-flow heat-source tower (CFHST)

Abstract

The heat-source tower heat pump (HSTHP), as a novel energy-saving unit, extracts low-grade thermal energy from air that can be a promising alternative of boiler in Yangtze River basin, China. A numerical model for analysis of the heat and mass transfer characteristics of a counter-flow heat source tower (CFHST) operating in winter is developed and validated by using experimental results. In this proposed numerical model, the changeable Lewis number is considered, and the effects of various operating, environmental including inlet air dry bulb temperature, inlet air humidity ratio, inlet air flow rate, inlet solution temperature and inlet solution flow rate on the thermal behavior of the heat source tower are studied. Furthermore, the proposed model will also be used to analyze the impact of the porosity and spacing of packing on the heat exchange in the CFHST. Finally, the moisture transfer characteristics inside CFHST under various environmental conditions are also studied. This work can provide a theoretical foundation for performance evaluation and practical design of CFHST.

Simulation Research on the Heating Performance of the Combined System of Solar Energy and Heat-Source Tower Heat Pump in a Hot Summer and Cold Winter Area

“…Huang et al [8] used a numerical method to compare and analyze the performance of OHTHP and traditional ASHP, and discovered that compared with traditional ASHP, the efficiency of OHTHP in summer and winter increased by 23.1% and 7.4%, respectively. Lu et al [13] established the prediction correlation of heat and mass transfer of an open-type heat-source tower by theoretical analysis and a numerical method. Fujita et al [14] fitted the relationship between the mass transfer coefficient and gas-liquid flow through experiments.…”

Effects of the operation parameters of a closed-type heating tower on the performance of heating tower heat pump system

“…Later, they improved the model to calculate the state parameters of air and water at any position inside the Heating Tower (Tan and Deng, 2003). Lu et al (2017) set up a model in which a variable Lewis number is considered, the results show that an increase in the air dry bulb temperature can significantly boost the sensible heat transfer and slightly reduce the transfer of latent heat. Wen et al (2012) conducted studies on the heat transfer coefficient between liquid and air.…”

Performance comparison of a heating tower heat pump and an air-source heat pump: A comprehensive modeling and simulation study

“…Wen et al [12] calculated the heat transfer coefficient of a cross-flow heating tower by assuming Lewis number equal to one and using the coupled heat and mass transfer model. To advance Wen's study, Lu et al [13] conducted a numerical study of a counter-flow heating tower considering the changeable Lewis number. However, the heat transfer coefficient was taken from a study on a super large cooling tower for a power plant, which had a completely different process from the heating tower used for buildings.…”

“…However, the heat transfer coefficient was taken from a study on a super large cooling tower for a power plant, which had a completely different process from the heating tower used for buildings. In order to calculate more valid heat and mass transfer coefficients, Huang et al [13] experimentally investigated the heat and mass transfer characteristics in a crossflow heating tower. More specifically, both heat and mass transfer coefficients were obtained using a finite difference method without the pre-assumption of Lewis number.…”