Modeling of a hybrid heat supply system for typical rural houses

Abstract

Relevance: this article investigates the hybrid heating system (HHS) of a typical rural house, which consists of a combination of a traditional heating system with a boiler unit (BU), a hot water supply (HWS) with an electric water heater, and a system based on renewable energy sources (RES) such as a heat pump unit (HPU) and a solar collector (SC). In the proposed HHS, the main energy units based on RES are the vapor-compression heat pump unit (HPU) and the solar collector (SC). The main thermodynamic parameters of the HPU include heat output and the heating coefficient, while for the solar collector, the key indicators are heat output and collector efficiency. To determine these parameters for the object of study, an energy balance equation for the rural house with the HHS is proposed.

Aim: is to model and study the hybrid heat supply system (HSS) of a typical rural house, which consists of a combination of a traditional heating system with a boiler unit (BU), hot water supply (HWS) with an electric water heater and a system based on renewable energy sources (HPU, SC).

Methods: the work used methods of mathematical modeling, theoretical foundations of heat engineering, similarity theory, experimental study of heat exchange processes and generalization of experimental results.

Results: the suggested mathematical model of the HHS for a typical rural house (1) allows for calculating the heat and electricity production and consumption, as well as the main thermodynamic characteristics for each hour of operation of the system’s key equipment. An analysis of the thermal balance of typical rural houses built in the Kashkadarya region revealed that for a typical rural house with a heating area of 144 m² and a heating volume of 432 m³, the average thermal load on the heating system is 13.8–14.0 kW, on the cooling system it is 10.1 kW, and on the hot water supply system it is 1.3 kW. The energy efficiency of using the HHS based on the HPU, according to our calculations, is 57–60%, meaning that the use of the HPU in heating systems for typical rural houses can reduce traditional fuel consumption by 1.57–1.60 times during the heating period. The use of the HPU in the heating period of a rural house with an area of 144 m² can save 1900 m³ of natural gas. With an average natural gas consumption in the heating period of 3300–4000 m³, the gas savings amount to 57–48%. The use of the SC results in savings of 33–27%, and the rational combination of “HPU + SC” provides savings of 75–90%.