Experimental and theoretical investigation of small-scale cooling system equipped with helically coiled evaporator and condenser

Utilizing helically coiled tubes evaporator and condenser in cooling applications is promising due to their higher heat transfer coefficients compared to straight tube because of the effect of centripetal forces. With growing interest in miniature and efficient refrigeration systems, small helical coil diameter can offer significant advantages in terms of being compact, lightweight, and improved coefficient of performance (COP). This article describes a performance study of small-scale vapour compression cooling system (100Wcooling capacity) equipped with shell and helically coiled tube evaporator and condenser. A detailed mathematical model has been developed for this system based on thermodynamic principles and relevant heat transfer correlations. The model was validated using experimental results from a representative small size cooling system with agreement of +/- 5 per cent. The model was then used to carry out performance optimization in terms of the evaporator and condenser geometric parameters including helical coil diameter, tube inside diameter, and surface area ratio. For the range of geometrical parameters investigated, the model predicts that as the coil diameter decreases, the Cooling COP improves.