Thermodynamic Performance Investigation of a Small-Scale Solar Compression-Assisted Multi-Ejector Indoor Air Conditioning System for Hot Climate Conditions

Abstract

In year-round hot climatic conditions, conventional air conditioning systems consume significant amounts of electricity primarily generated by conventional power plants. A compression-assisted, multi-ejector space cooling system driven by low-grade solar thermal energy is investigated in terms of energy and exergy performance, using a real gas property-based ejector model for a 36 kW-scale air conditioning application, exposed to annually high outdoor temperatures (i.e., up to 42 °C), for four working fluids (R11, R141b, R245fa, R600a). Using R245fa, the multi-ejector system effectively triples the operating condenser temperature range of a single ejector system to cover the range of annual outdoor conditions, while compression boosting reduces the generator heat input requirement and improves the overall refrigeration coefficient of performance (COP) by factors of ~3–8 at medium- to high-bound condenser temperatures, relative to simple ejector cycles. The system solar fraction varies from ~0.2 to 0.9 in summer and winter, respectively, with annual average mechanical and overall COPs of 24.5 and 0.21, respectively. Exergy destruction primarily takes place in the ejector assembly, but ejector exergy efficiency improves with compression boosting. The system could reduce annual electric cooling loads by over 40% compared with a conventional local split air conditioner, with corresponding savings in electricity expenditure and GHG emissions.

Energy and exergy simulation analysis and comparative study of solar ejector cooling system using TRNSYS for two climates of Iran

“…where ṁ, 𝐴, 𝜌 are mass flow rate (kg/s), area of the solar collector (m 2 ), density (kg/m 3 ), respectively. By using 𝑉 , then the Reynolds number (𝑅 𝑒 ) is obtained via Equation (3).…”

“…Nowadays, majority of such technologies are utilized by vapor compression systems which consume significant electrical energy primarily generated by power plants which consume fossil fuels, including Mazut which are all harmful pollutants for the environment [2] . Solar cooling technology has been an attractive subject for various researches for replacing the common cooling systems due to its non-polluting character and compatibility with the environment [3] . Among such cooling technology, the solar ejector cooling system (SECS) is subjected to wide research activities because of its unique ability to operate with low thermal grade heat supply, such as solar energy.…”

Sustainable Buildings: Heating, Ventilation, and Air-Conditioning

“…Here, we provide a brief review of the articles [7][8][9][10][11][12][13][14] published in the Special Issue. A graphical summary of the key areas covered in the Special Issue is shown in Figure 2.…”

“…Eveloy and Alkendi (2021) [13] proposed a solar-assisted multi-ejector space cooling system as an alternative to conventional air-conditioning to minimise energy demands in buildings in hot climates. A mathematical model was used to carry out the evaluation.…”