Design of a Solar Dryer with Integrated Thermal Storage based on Sorption Materials

Abstract

Solar drying is not modern technology, but it is a traditional way to save nutrition so it can be consumed later. Dried mangoes were introduced as an idea that it will develop an added value for the mangoes in West Africa and Burkina Faso where there is massive production. The target group was the small mangoes producers and companies. Non-governmental organizations (NGOs) distributed solar dryers on women, and they conducted training for them. By the time the solar dryer seemed to be inefficient, the majority left it, and the companies now are using gas-fired dryers for drying mangoes. Burkina Faso is not a gas producer county, and it imports it from the Codivoir, the gas price is quite high even that it is subsidized. It represents 15 -30 % of the total cost of the drying process. It is known that the national strategy is about removing natural gas subsidies, which will make the drying activity unprofitable according to mangoes producers. Since Burkina Faso has abundant solar irradiance, it is preferable to utilize it in drying mangoes. Some models were developed for solar dryers for mangoes in the past, but none of them is working. The reason is the climate conditions in the harvesting season of mangoes, relatively high relative humidity of the air combined with relatively low solar radiation. Sorption material is the technology is being used nowadays to perform high-density energy storage. The addition of such thermal energy storage can be part of the solution because it will absorb the excess humidity in the air, which will enhance the air capability to absorb the moisture in the mangoes. Also using storage will increase the working hours by storing the available solar irradiance and using them at night.