DETERMINATION OF THE THERMOPHYSICAL PROPRTIES OF NSUKKANUT: A SOLID ABSORBENT FOR SOLAR REFRIGERATION

Abstract

The thermophysical properties of 'Nsukkanut', - a CaCl₂/CaSO₄ absorbent mixture used in solid absorption solar refrigeration [1], were studied in this report. The transient experimental technique of Beck and Al-Araji [12] was used in determining the effective thermal conductivity, specific heat and bulk thermal diffusivity of granular (2.8 - 6.35 mm sizes) parkings of the absorbent. Additionally, the parking density crushing stress percentage swell and degree of refrigerant - NH₃ absorption were determined. Effective k, c and a values were in the ranges of 0.098 - 0.111 W/mk, 1.123 -1.696 kJ/kg K and 1.404 - 1.053.10^-7 m²/s, respectively, for a parking density of 621.4 kg/m³. Average crushing stress, the percentage swell and absorption factor values 018.17 N/mm², 7.96% and 62.1 % respectively, obtained in this report compared well with values of 8.10 N/mm², 11.6% and 59.5% correspondingly, as reported in [11].

The effect of aluminium as a thermal conductivity improvement additive, on the thermophysical properties of the absorbent, were also studied. For aluminium fractions of up to 3% by mass, no sustained improvement in thermal properties were observed, while the strength and swell properties deteriorated