Abstract: The energy efficiency of spiral plate heat exchangers has a direct impact on the overall energy efficiency of the units in petrochemical and refrigeration industry. Firstly, through theoretical analysis, it was determined that adopting energy efficiency index K/P which had a comprehensive reflection on both heat transfer and flow characteristics was suitable to evaluate the energy efficiency of spiral plate heat exchangers. Secondly, empirical approach was taken to research the energy efficiency level of four typical spiral plate heat exchangers and its influencing factors. The results show that the key structure parameters equivalent diameter de and distance column density had significant impact on K/P of spiral plate heat exchangers. The average values of energy efficiency indicator K/P of the prototype models at each flow rate were 1.00, 0.85, 1.49 and 1.97 respectively. There were big differences among the average values. And the level of energy efficiency had nothing to do with the heat exchange area; energy efficiency indicator K/P was affected by the flow velocity dramatically, and decreased with the increase of the flow rate, while it was less affected by the fluid inlet temperature; the energy efficiency level of the four prototypes was stable at different flow rates and different inlet temperatures. Lastly, a complete set of energy efficiency evaluation method for spiral plate heat exchangers was proposed. The energy efficiency of 285 spiral plate heat exchangers was calculated and the energy efficiency rating was divided according to the calculation.

Key words: spiral plate heat exchanger, structure parameters, thermal parameters, energy efficiency index, energy efficiency evaluation