Optimization Design And Research Of PTC Heater Based On Comprehensive Performance Evaluation

The effective use of existing energy resources and the improvement of energy efficiency have become hot issues that experts and scholars in various countries are concerned about.Heat exchanger is a common industrial equipment.The cost of heat exchangers often accounts for 30% to 40% of investment in modern chemical companies.In the air-conditioning HVAC industry,the heat exchanger weight accounts for more than 30% of the total weight of the unit,and the power consumption for heat exchange will be about 25% of the total power consumption.The PTC(Positive Temperature Coefficient)heater is the safest,most reliable,most efficient and cleanest electric heater available today.The economy of PTC heaters is extremely critical in the actual production and life while only the optimization design based on the thermal performance index is currently available.Researching an optimization method that considers the thermal performance and economy of the PTC heater,therefore,has important theoretical significance and engineering application value.In this paper,the PTC heaters are analyzed by thermal transfer theory and entransy theory,and the functions of temperature distribution function,thermal resistance and heat transfer efficiency of PTC heaters are obtained.Combined with the economical index temperature difference effectiveness,the comprehensive performance evaluation function of the PTC heater is proposed.The structure of PTC heater is optimized on the goal of the minimum number of entransy dissipation and the maximum value of the overall performance evaluation function,respectively,of which the results is verified by simulation and analyzed by thermal economics.Optimization and analysis verification results are as follows:1)Improved thermal performance of PTC heaters increased by 8.37% to 12.59%;Optimized PTC heaters based on the minimum number of entransy dissipation are better than those based on the maximum value of the overall performance evaluation function with performance increased by 0.97% to 4.22%.PTC heaters of rectangular heat dissipation structure are superior to those of triangular heat dissipation structure in the both optimization methods.2)The overall economy of the optimized PTC heater improves with the decrease of power consumption and the increase of cost.For manufacturing companies,the optimized PTC heater based on the overall performance evaluation function has a 1.27%-3.16% lower cost than those based on the minimum entransy dissipation number,and the power consumption cost increases slightly.The overall economic performance is based on the optimization of PTC heaters with the highest overall performance evaluation function value.The optimized PTC heater based on overall performance evaluation has better overall economy than the other.3)The optimization method based on the evaluation of the maximum value of the overall performance is a reasonable optimization method that considers both the thermal performance and the economy at the same time.