Energy efficiency evaluation method for plate heat exchanger

In heat exchangers, heat transfer between the cold and the hot fluid consumes pumping power. Evaluating the energy efficiency of this process scientifically and quantitatively is an urgent issue for both academic research and industrial applications, and has important significance to energy saving and emission reduction. We comprehensively analyzed the flow and heat transfer characteristics of water-water heat transfer process without phase-change in a heat exchanger, and proposed the energy efficiency index (=k/▽pⁿ, k is overall heat transfer coefficient and ▽p is flow pressure gradient). EEI reflects the inherent energy efficiency properties of a heat exchanger, which represents the overall heat transfer coefficient per equivalent flow pressure drop consumption. At a given temperature difference and fluid flow rate, for the heat exchangers with the same heat transfer area and fluid flow length, bigger EEI means a lager heat transfer rate per equivalent pumping power consumption. EEI is independent on the heat transfer area; no dependence or weak dependence on the flow velocity can be achieved by choosing the index n reasonably, indicating a good stability of EEI. Evaluation result based on national standard of heat exchanger performance test measured could represent the energy efficiency of the heat exchanger. Combined with the water-water heat transfer process without phase-change flow and heat transfer performance database of the plate heat exchangers, the value of index n and the overall EEI distribution of plate heat exchangers in industry are obtained, providing a basis for the classification of the energy efficiency of plate heat exchangers.