High-efficiency solar cooling

How efficiently can solar radiation realistically be converted into cooling power? With recent advances in the solar and chiller fields, net coefficie nts of performance (COPs) of 100% and above should be attainable (i.e. 1 kW of incident solar radiation yielding 1 kW or more of cooling power) with e xisting technologies. The performance leap, relative to current state-of-th e-art solar cooling systems, stems from the introduction of solar fiber-opt ic mini-dish systems that can deliver high-temperature heat at high solar-t o-thermal conversion efficiencies. Driving efficient commercially-available double-stage absorption chillers, solar mini-dish systems should be able t o realize net COPs of around 1.0. A further boost in net COP to around 1.4 can be achieved by modifying the conventional scheme to a thermodynamic cas cade that takes maximal advantage of high-temperature input heat. The casca de comprises a solar-fired gas micro-turbine producing electricity that dri ves a mechanical chiller, with turbine heat rejection running an absorption chiller. An additional virtue is that the energy of concentrated sunlight can be stored compactly as ice produced at a retrofitted evaporator of the mechanical chiller. The compactness and modularity of solar mini-dish syste ms opens the possibility for small-scale ultra-high-performance solar cooli ng systems. (C) 2000 Elsevier Science Ltd. All rights reserved.