Analysis and testing of a novel cascaded adsorption-compression chiller for industrial applications

Adsorption technology has experienced high R&D efforts in the last decades, becoming a mature technology with several systems on the market. Many features make the adsorption systems attractive: electricity consumption extremely low, limited maintenance needed, low noise operation and the possibility to be driven even by low-grade waste heat (< 90°C). Also electric chillers present some unique features: high precision in temperature regulation and fast response to temperature fluctuations. Nonetheless, strict international regulations in terms of seasonal efficiency requirements and environmental issues related to the refrigerants used, determine new challenges for this field, especially for commercial and industrial installations. In such a background, aim of this paper is to report an experimental analysis on a double-stage chiller realized by coupling in cascade an adsorption chiller and a vapour compression unit. Main feature in the operation of such system is the possibility to use waste heat from process, which is usually available in industrial applications, for the operation of a silica gel/water adsorption chiller (first stage). Chilled water obtained at high electrical efficiency in the first stage is then employed for cooling of the condenser in a traditional vapour compression chiller (second stage), thus working in a more favourable condition. To this goal, the experimental results from a testing campaign performed at CENTROPROVE of CNR-ITAE are presented. Results clearly show that it is possible to double the seasonal efficiency if compared with a standard electric chiller performance.