Utilization of a Solar Greenhouse as a Solar Dryer for Drying Dates under the Climatic Conditions of the Eastern Province of Saudi Arabia

Abstract

The goal of this project was to evaluate the feasibility of using a solar greenhouse as a solar dryer for drying dates. We attempted to analyze the thermal performance and thermal balance of the solar greenhouse. An experimental gable-even span greenhouse (solar greenhouse) was installed at the experimental research station at King Faisal University (latitude 25.4ºN, longitude 49.6ºE, and altitude 142 m above sea level) and functioned during October 2010. We evaluated the thermal performance analysis of the solar greenhouse (active or dynamic system) based on the thermal balance equations. The obtained results revealed that the daily average solar energy available outside the solar dryers was 15.921 kWh, and 12.335 kWh was available inside the solar greenhouse for an average effective transmittance of 77.48%. Of the 12.335 kWh available inside the solar greenhouse, 7.414 kWh was converted into useful heat gain that could be used for the drying process, 3.947 kWh was lost by conduction and convection, and 0.686 kWh was lost by thermal radiation. The solar energy available inside the solar greenhouse produced a 14.1°C increase in the inside air temperatures versus the outside temperature (33.6°C) and reduced the relative humidity of the inside air versus the outside air (35.3%) by 9.6%. The daily average overall thermal efficiency of the solar greenhouse during the experimental period was 57.2%. Consequently, 42.8% of the solar energy available inside the solar greenhouse was lost. The predicted thermal balance for the solar greenhouse was well validated with that measured during the experimental period (r= 0.999) indicating an excellent agreement.

Evaluación térmica y financiera del proceso de secado de grano de café en un secador solar activo tipo invernadero

“…The difference between the internal temperature and the environment is greater than the difference of 13.6 °C reported by Menya and Komakech (2013) in a greenhouse dryer, located in Uganda, and also greater than the temperature difference of 12.8 °C reported by Monrudee et al (2001) and 14.1 °C reported by Almuhanna (2012), both in greenhouse dryers, and less than the maximum difference of 27 °C reported by es mayor a la diferencia de 13.6 °C reportada por Menya and Komakech (2013) en un secador tipo invernadero, localizado en Uganda, e igualmente mayor a la diferencia de temperatura de 12.8 °C reportada por Monrudee et al (2001) y de 14.1 °C reportada por Almuhanna (2012), ambos en secadores tipo invernadero, e inferior a la diferencia máxima de 27 °C reportada por Ferreira et al (2008) mediante una chimenea solar o a la diferencia de 29.9 °C de temperatura al interior de un secador solar sobre la temperatura ambiental, reportada por Sreekumar (2013).…”

“…Por lo tanto, la eficiencia térmica total es la relación de la ganancia de calor útil a la energía solar disponible en el interior del secador solar (Almuhanna, 2012). Así, la eficiencia de un secador solar es una medida de la eficacia con que se utiliza la radiación solar por el sistema para secar el producto y evalua su rendimiento (Keke et al, 2014y Mustapha et al, 2014.…”

“…Therefore, the total thermal efficiency is the ratio of the gain useful heat of solar energy available inside the solar dryer (Almuhanna, 2012). Thus, an efficiency from a solar dryer it is a measure of the effectiveness with which used the radiation solar system to dry the product and evaluate your performance (Keke et al, 2014 andMustapha et al, 2014).…”

Design, fabrication and performance evaluation of solar dryer for banana

“…It is still used in domestic up to small commercial size drying of crops, agricultural products and foodstuff such as fruits, vegetables, aromatic herbs, wood etc. contributing thus significantly to the economy of small agricultural communities and farms [4][5][6].…”

A Comprehensive Review on Greenhouse Drying Technology

“…Coconuts dried in dryer were reported to be free from dust, dirt, damage by birds and infections by bacteria and fungus [40]. A new approach of utilizing a solar greenhouse (gable even span) as a solar air heater for drying dates was studied [41].…”