We decompose labor-productivity growth into components attributable to (1) technological change (shifts in the world production frontier), (2) technological catch-up (movements toward or away from the frontier), and (3) capital accumulation (movement along the frontier). The world production...

The top cover of a flat plate solar collector is generally exposed to wind. In indoor experiments it is necessary to simulate this wind. Correlations have been developed for the wind heat transfer coefficient over flat horizontal surfaces exposed to forced air flow, produced by industrial fans...

The thermal performance of any focussing-type solar cooker, where an unglazed/uuninsulated cooking pot is often used, depends to a great extent on wind conditions. Moreover, these cookers need frequent adjustments to track the Sun in order to keep the focus always at the bottom of the cooking...

The top heat-loss factor (Ut) of a box-type solar cooker varies with plate temperature, wind heat-transfer coefficient and ambient temperature. A method for correlating Ut with these variables is presented for a cooker with double glazing. A set of equations is developed for correlating data...

In the present study, drying experiments on mixed-mode solar dryer with cylindrical potato samples have been performed for a wide range of process variables. The variables investigated are absorbed thermal energy, air flow rate, food product loading density and sample thickness. A mathematical...

The paper presents a simple test procedure for determination of design parameters to predict the thermal performance of a box-type solar cooker. A series of out-door experiments were performed on the double-glazed solar cooker of aperture area 0.245m2 with a fibre body to obtain two figures of...

Thermal performance of a parabolloid concentrator solar cooker depends greatly on the wind speed. Experiments have been conducted to study the effect of wind speed on heat loss parameter F′UL and hence on thermal performance of the cooker under simulated wind conditions. Correlations have been...

Three somewhat different experimental test procedures may be employed for the determination of the optical efficiency factor, F′ηo, of a parabolloid concentrator solar cooker. The procedures are briefly described and typical results presented. The merits and drawbacks of each test procedure...