Abstract

Utilizing solar thermal energy or waste heat, adsorption chillers have emerged as pivotal air-conditioning systems in net zero buildings. Traditional models, operating at 50°C with a cooling tower at 33°C, exhibit suboptimal energy efficiency, yielding chilling water temperatures of merely 18~20°C. In this study, we propose leveraging a shallow geothermal energy system, operating at a cooler 22°C, to supplant the conventional cooling tower. By doing so, the coefficient of performance of the adsorption chiller can be enhanced from 0.18 to 0.4. We present two distinct adsorption-compression hybrid systems tailored for different seasons: Mode A, harnessing solar thermal energy to power the adsorption chiller for cold storage, thereby mitigating the load on the compression chiller during nocturnal operation; Mode B, generating 16°C chilling water to cool the compression chiller's condenser, thereby boosting compressor efficiency by 22%. Given that key construction components of villa-type green buildings already integrate shallow geothermal and solar thermal energy systems, the estimated minimum payback period for implementing the hybrid system stands at 2.1 years.

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