The paper presents a comparison between two different orientations of a vegetable greenhouse with respect to East-West axis in Romania. The solar irradiance received by the greenhouse is estimated based on isotropic clear sky analysis model. Interior air temperature profiles are numerically simulated all along a day, in winter and in summer. In order to maintain a constant interior air temperature during vegetation, heating and respectively cooling required loads are computed. Different profiles are obtained for the considered orientations. Based on these profiles, the numerical simulation reveal energy savings for the E-W orientation with respect to N-S one, both in summer and winter periods. The results might be used for designing the cooling and heating equipment ensuring the optimum microclimate inside the greenhouse

A simple effect one stage ammonia-water absorption cooling system fueled by solar energy is analyzed. The considered system is composed by a parabolic trough collector concentrating solar energy into a tubular receiver for heating water. This is stored in a fully mixed thermal storage tank and used in the vapor generator of the absorption cooling system. Time dependent cooling load is considered for the air conditioning of a residential two-storey house. A parametric study is performed to analyze the operation stability of the cooling system with respect to solar collector and storage tank dimensions. The results emphasized that there is a specific storage tank dimension associated to a specific solar collector dimension that could ensure the longest continuous startup operation of the cooling system when constant mass flow rates inside the system are assumed.

As part of the efforts to unify the various branches of Irreversible Thermodynamics, the proposed work reconsiders the approach of the Carnot engine taking into account the finite physical dimensions (heat transfer conductances) and the finite speed of the piston. The models introduce the irreversibility of the engine by two methods involving different constraints. The first method introduces the irreversibility by a so-called irreversibility ratio in the entropy balance applied to the cycle, while in the second method it is emphasized by the entropy generation rate. Various forms of heat transfer laws are analyzed, but most of the results are given for the case of the linear law. Also, individual cases are studied and reported in order to provide a simple analytical form of the results. The engine model developed allowed a formal optimization using the calculus of variations.