Multi-criteria optimization of heat recovery unit in terms of the climatic factor

Abstract

The use of heat pumps in exhaust air heat recovery systems is an effective energy-saving technology. Due to the increase in the number of refrigerants with different characteristics, a problem arises with making a decision on the use of a specific substance, taking into account the climatic features of a particular region. Multicriteria optimization methods adapted to solving this problem can be used taking into account the specified preferences for energy, environmental and economic factors. The TOPSIS method is used in this paper as one of the subtypes of the MADM multicriteria optimization method, which is adapted to solve the problem. The essence of the method is to find a Pareto-optimal alternative solution that is closest to the «ideal positive». The parameters of the heat pump unit are calculated in the EES program. The TOPSIS multicriteria optimization method is implemented as a computational procedure in the Excel environment. The working fluids R410A, R407C, R290, R134a and R1234yf are considered as alternatives. The climatic zones of the Russian Federation are represented by the cities of Saint Petersburg, Petrozavodsk, Sochi, Omsk, Krasnodar and Anadyr. The optimal alternative is selected taking into account the preferences specified by the weighting factors. The results of multi-criteria optimization are presented as a function of the climatic factor of the HSDD, which allows them to be used for any locality. According to the optimization results, it is revealed that with an equal assessment of the significance for six cities of the Russian Federation, the refrigerant R1234yf has a rating higher than the others by 21 % – 23 %. Optimization based on energy efficiency revealed significant advantages in refrigerants R410A and R134a with a difference of 2 % – 11 %. For regions with a cold climate, it is more economical to use refrigerant R1234yf, while for regions with a moderate climate, the best option is R134a.