This paper introduces the photosynthesis-stomatal conductance coupled model, well known and frequently used in the studies of vegetation-atmosphere interaction, to be incorporated into the studies of modeling greenhouses’ microclimate. The use of this model, unlike many of other models in the literature, allows accurate modeling of stomatal conductance for many plant types and under several environmental conditions. It also guarantees the modeling of the photosynthesis process ,which is important for microclimate and CO2 enrichment purposes, due to the direct coupling between photosynthesis and stomatal conductance in this model. Although the many advantages of this model, the many details associated with it may be the reason behind not being used in greenhouse microclimate modeling studies. Thus, this paper comes with an aim of facilitating the use of this model and encouraging modelers of greenhouses’ microclimate to use this powerful model by providing them the necessary background for the treatment of the model in a well organized form that contains all the necessary and required information they may need in their use of the model. In this paper, the photosynthesis-stomatal conductance coupled model is introduced by first illustrating briefly the biochemical background of the photosynthesis process and then introducing the accurate biochemical model that represents it. Then the photosynthesis-stomatal conductance coupled model is presented with its analytical solution methodology that gives accurate estimation of the photosynthesis rate and the stomatal conductance. Finally, validation of the model results with available experimental data is performed for a representative crop type under different environmental conditions. This validation proves the accuracy of the model in predicting the photosynthesis rate and in turn the stomatal conductance.

Abstract: A residential scale solar driven adsorption cooling system was designed, constructed, and operated at Assiut University, Assiut city, Egypt. The system consists of evacuated tube with back reflectors solar collector arrays field of total area 36 m2, a silica gel- water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water storage tanks of volumes 1.8 m3 and 1.2 m3 respectively. The system was designed to operate with or without both cold and hot thermal buffers. The aim of this study is to investigate experimentally the effect of hot and cold buffers on performance of the chiller, solar collectors, and the overall system performance. The experimental results show that both the chiller and solar collectors operates steadily with integration of the hot storage. In addition, the chiller performance is higher with the hot storage with an increase in the cooling capacity of about 18% and about 10 % in the COP than the case without integration the hot thermal buffer. Also the results show that, the existence of the hot storage is necessary, on the system as it effect on both the collector field and chiller performance. Moreover, the cold storage has no significant effect on the chiller and collector’s performance. The chiller performance is sensitive to any fluctuation in the chilled water inlet temperature. The collector’s efficiency is slightly higher without the cold storage, due to the lower inlet temperature to collector field.

Abstract: A residential scale solar driven adsorption cooling system was designed, constructed, and operated at Assiut University, Assiut city, Egypt. The system consists of evacuated tube with back reflectors solar collector arrays field of total area 36 m2, a silica gel- water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water storage tanks of volumes 1.8 m3 and 1.2 m3 respectively. The system was designed to operate with or without both cold and hot thermal buffers. The aim of this study is to investigate experimentally the effect of hot and cold buffers on performance of the chiller, solar collectors, and the overall system performance. The experimental results show that both the chiller and solar collectors operates steadily with integration of the hot storage. In addition, the chiller performance is higher with the hot storage with an increase in the cooling capacity of about 18% and about 10 % in the COP than the case without integration the hot thermal buffer. Also the results show that, the existence of the hot storage is necessary, on the system as it effect on both the collector field and chiller performance. Moreover, the cold storage has no significant effect on the chiller and collector’s performance. The chiller performance is sensitive to any fluctuation in the chilled water inlet temperature. The collector’s efficiency is slightly higher without the cold storage, due to the lower inlet temperature to collector field.

Abstract: A residential scale solar driven adsorption cooling system was designed, constructed, and operated at Assiut University, Assiut city, Egypt. The system consists of evacuated tube with back reflectors solar collector arrays field of total area 36 m2, a silica gel- water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water storage tanks of volumes 1.8 m3 and 1.2 m3 respectively. The system was designed to operate with or without both cold and hot thermal buffers. The aim of this study is to investigate experimentally the effect of hot and cold buffers on performance of the chiller, solar collectors, and the overall system performance. The experimental results show that both the chiller and solar collectors operates steadily with integration of the hot storage. In addition, the chiller performance is higher with the hot storage with an increase in the cooling capacity of about 18% and about 10 % in the COP than the case without integration the hot thermal buffer. Also the results show that, the existence of the hot storage is necessary, on the system as it effect on both the collector field and chiller performance. Moreover, the cold storage has no significant effect on the chiller and collector’s performance. The chiller performance is sensitive to any fluctuation in the chilled water inlet temperature. The collector’s efficiency is slightly higher without the cold storage, due to the lower inlet temperature to collector field.

Abstract: A residential scale solar driven adsorption cooling system was designed, constructed, and operated at Assiut University, Assiut city, Egypt. The system consists of evacuated tube with back reflectors solar collector arrays field of total area 36 m2, a silica gel- water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water storage tanks of volumes 1.8 m3 and 1.2 m3 respectively. The system was designed to operate with or without both cold and hot thermal buffers. The aim of this study is to investigate experimentally the effect of hot and cold buffers on performance of the chiller, solar collectors, and the overall system performance. The experimental results show that both the chiller and solar collectors operates steadily with integration of the hot storage. In addition, the chiller performance is higher with the hot storage with an increase in the cooling capacity of about 18% and about 10 % in the COP than the case without integration the hot thermal buffer. Also the results show that, the existence of the hot storage is necessary, on the system as it effect on both the collector field and chiller performance. Moreover, the cold storage has no significant effect on the chiller and collector’s performance. The chiller performance is sensitive to any fluctuation in the chilled water inlet temperature. The collector’s efficiency is slightly higher without the cold storage, due to the lower inlet temperature to collector field.