ABSTRACT

The project work is on the effect of varying solar collector surface area on performance of a post harvest solar dryer for drying agricultural produce .The four solar collectors with lengths of 450mm, 900mm, 1350mm and 1800mm respectively and each has a width of 400mm. The dryers, constructed of ply-wood each has length of 500mm, and width of 440mm, each dryer was attached to solar collector of different surface area. The dryers were fitted with three trays each for loading the product to be dried and two thermometers each (one on top of the top tray and the other below the lower tray) for temperature readings to be taken. The performance test was carried out using three crops as test samples (tomatoes, pepper and moringa) which are locally sourced. Results of the test carried out using the solar collector incorporated with the dryers shows that the surface area of the collector has a significant effect on the performance of the dryer. Collector ‘A’ with surface area of 180 (m2) has average drying rate of 0.22 (g/min) when the dryer was loaded with tomatoes, 0.30 (g/min) when the dryer was loaded pepper and 0.15 (g/min) when the dryer was loaded with moringa. Collector ‘B’ with average surface area of 360(g/min) has an average drying rate of, 0.29 (g/min) when loaded with tomatoes, 0.32 (g/min) when loaded with  pepper and 0.17 (g/min) when loaded with moringa, collector “C” with average surface area of 540 (m2) has average drying rate of 0.29 (g/min) when loaded with tomatoes, 0.32 (g/min) when loaded with pepper and 0.20 (g/min) when loaded with moringa, collector “D” with average surface area of 720 (m2) has an average drying rate of  0.30 (g/min) when loaded tomatoes, 0.34 (g/min) when loaded with pepper and 0.20 (g/min) when loaded with moringa. So also from the results obtained from the analysis of variance (ANOVA) through completely randomize design (C.R.D). The tabulated values of “F” at both 5% and 1% level of significance when testing with tomatoes was less than the calculated values gotten. The tabulated values are: 5% level = 2.36, 1% = 4.38 while the computed value gotten was 6.32468. The tabulated values of F at 5% and 1% level of significance are 2.36 and 4.38 respectively. While testing with pepper, the competed value of F was 11.5165. The tabulated values of F at 5% and 1% level of significance are 3.01 and 2.72 respectively. While testing with moringa, the computed value of F was 5.36892, the tabulated values of “F” at 5% and 1% level of significance are 1.328 and 1.268 respectively. This shows that the variation in surface area of the solar collectors has a significant effect on the temperature generated by the collectors, hence affecting the rate at which the dryers dry the products. The dryer attached to collector ‘D’ with dimension of 1800mm x 400mm (which has the largest surface area) has the highest temperature during the period of testing. Statistical analysis of the data was conducted using analysis of variance (ANOVA) using Completely Randomized Design (CRD).It was through the statistical analysis that the ranking of the solar collectors was observed.

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