A study of capillary-assisted evaporators

The paper presents a comparative study of the effect of porous layer parameters on the thermal performance of capillary-assisted evaporators. The results show that there are optimum particle sizes that are associated with maximum boiling heat rates and heat transfer coefficients. The results also show that the layer thickness has monotonic effect on the evaporators’ performance but its impact is less pronounced compared to that of the particle size. The trends are explained in terms of the contradicting effects that exist within the layer. Agreement in trend, and to a lesser degree in value, is obtained between the analytical and experimental results with the discrepancy explained in terms of the inaccuracies of the empirical formulae used and the effect of condensation on the tube wall thermal resistance. Boiling heat transfer coefficients of up to 5 kW/m2 °C were achieved.