Simple method for estimating energy efficiency of industrial heat pumps available on the Japanese market
Industrial heat pumps are recognized as an important technology for decarbonizing industries due to their high energy efficiency and ability to be electrified with low carbon electricity. In Japan, various types of industrial heat pumps have been commercialized to accommodate a wide range of industrial heating processes. This diversity requires time and effort when examining the applicability of heat pumps, which is one of the factors hindering their introduction. This study aims to develop a unified and simple method for estimating the energy efficiency of industrial heat pumps. First, energy performance data on industrial heat pumps available in the Japanese market are collected and analyzed. Then, based on the regression analysis, two types of correlations between Lorenz efficiency and logarithmic mean temperature lift are developed. The first-type correlation can estimate the average COP (coefficient of performance) of industrial heat pumps with single-stage cycles with an accuracy of approximately within ±10%. On the other hand, the second-type correlation represents the highest performance of existing technologies including two-stage cycles and cascade cycles. Both correlations can be calculated by inputting 6 parameters: heat source medium, heat sink medium, heat source inlet and outlet temperatures, and heat sink inlet and outlet temperatures.