This paper presents a design and a performance comparison between three temperatures 38,40 and 42OC for manufacture yoghurt by a solar-energy (SE) to obtain suitable temperature for best quality product. Thermal analysis was performed without load to tests the effect of high air mass flow on incubator and the collector efficiency and effectiveness under three various air mass flow rate ( 0.031, 0.046 and 0.062 kg/s). The resultant yoghurt samples were tested to compared with the other yoghurt produced by an electrical incubator. The analysis of results showed that the produced yoghurt at 42 OC was a high quality one compared to those with others temperature. It noticed that the yoghurt produced by (SE) had a high quality compared to electrical energy. The obtained data cleared that the percentage of collector efficiency were ranged from 40.24 to 86.76 , 28.05 to 68.19 and 20.20 to 43.55 while the effectiveness were ranged from 26.83 to 48.48, 25.30 to 41.46 and 31.25 to 39.84 in addition to that the percentages of incubator efficiency ranged from 9.66 to 37.05, 16.11 to 58.64 and 29.92 to 61.53 while the effectiveness ranged from 35.34 to 54.62, 28.44 to 57.14 and 24.82 to 70.96 for exhausted fan speed 1.5, 2.2 and 3 m/s respectively. Collector efficiency increased while incubator decreased with increase in the air flow rate. The effectiveness increased for collector and incubator by exceed air flow rate. Finally an economic evaluation was calculated using the criterion of payback period which is found very small 1.34 years compared to the life of the incubator 25 years.
MENU
