Optimization of novel heat exchanger design for the application to low temperature lift heat pump

The low temperature lift heat pump (LTLHP) utilizes a small difference between the condensing and evaporating temperatures of a working fluid. It requires a larger heat transfer area, a higher volume flow rate, and a higher temperature of heat source fluid, as compared to the typical heat pump system. In order to improve the performance of conventional plate heat exchangers, a novel heat exchanger with new geometries has been developed for application in the LTLHP. The main design development strategies were regulating the flow area ratio and offsetting plates in order to balance the heat transfer and pressure drop of the heat exchanger. The design parameters of the novel heat exchanger design were optimized with multi-scale approaches. Once the refrigerant-side geometry is properly designed according to the water-side performance, the overall heat transfer capacity of the novel heat exchanger is predicted to be higher than that of PHX by 53–204%. This can decrease the cost of the heat exchanger and increase the performance of the LTLHP system.

► Novel heat exchanger concept was developed for the low temperature lift heat pump.
► Performance of the novel heat exchanger was numerically investigated.
► Online approximation-assisted optimization was applied for the novel heat exchanger.