A new thermal–hydraulic process for solar cooling

This paper presents a novel and innovative solar cooling, air-conditioning process for individual buildings, which uses common flat plate collectors. The principle of the process is based on an original coupling between an engine cycle and a reverse cycle, which are respectively a Rankine-like cycle and a reverse Rankine cycle. The coupling of these dithermal cycles produces a global tri-thermal system with an internal work transfer realised by an inert liquid LT which plays the role of a liquid piston. These cycles use their own working fluid (hydro-fluorocarbons (HFCs)) and their performances are close to corresponding Carnot cycles. This new system appears as an attractive alternative for solar cooling technologies due to its ability to use low temperature driving heat source. Several versions of the thermo-hydraulic system have been investigated in order to obtain the best cost-effective compromise for an individual building application. A modelling of the process coupled to 20 m2 of flat plate solar collectors and providing 5 kW cooling capacity has been developed by using the concept of equivalent Gibbs systems. This model determines the performances of the machine operating in unsteady-state mode. It seems that the performances are very competitive with existing solar cooling systems.

► We present a new solar cooling process that couples engine and reverse Rankine cycles.
► The working fluid pair R236fa/R134a is selected for air-conditioning application.
► We evaluate the performances of two process versions through a dynamic modelling.
► A COP of 0.49 is achieved by using heat at 70 °C and producing cold at 12 °C.
► Attractive solar cooling process that can use low temperature driving heat source.