RESUMO
The paper presents the design, development and investigative studies into the use of a solar hot case/food warmer. The solar hot case can prove to be highly useful to the persons who carry hot food to their workplaces for lunch and eat it 4-5 h later. It can help keep food warm and infection free, by maintaining the food at an elevated temperature. The solar hot case has been developed with a total aperture area of 0.673 m2. The energy requirements for food warming have been calculated and found to be around 62 kJ in summer and 90 kJ in winter for an average lunch box of mass 0.25 kg containing 0.4 kg of food. The design of the solar hot case has been prepared on the basis of the food warming calculations to allow around ten lunch boxes to be warmed simultaneously. A computer program based on the solar radiation geometry and an ASHRAE model has been prepared to study the energy available in various months and to estimate the solar energy interception by the solar hot case. The results show that the energy absorbed by the system at an instant varies from around 300 to 1400 kJ/m2h in winter and 1000-2000 kJ/m2h in summer. Experimental in-field observations related to the temperature profiles of the developed system are also reported.
