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This paper studies the performance of a proposed desiccant assisted air conditioning system operating under the hot and dry climate conditions of Mosul city, Iraq. The proposed system consists of three stages: indirect/direct evaporative cooler, an enthalpy wheel, and a traditional vapor compression system. The performance of the suggested system is compared with that of the vapor compression system operating at the same conditions. The simulation results showed that an optimum rotational speed of 12.5 rpm is required for the enthalpy wheel to achieve the best system performance. The simulation results also showed the ability of the proposed system to achieve a power consumption saving of 51.03%, in the ventilation mode, and 22.93%, in the mixing mode with a ventilation mixing ratio of 0.4 when compared to the vapor compression system.

Solar energy is the best alternative to limited fossil fuels. The foremost important means of utilizing solar energy are solar collectors. The most common types of solar collectors are flat plate solar collectors. A great deal of theoretical research has been conducted to enhance the flat plate solar collector efficiency. One effective way to increase the efficiency is by using an improved thermal properties fluid as nanofluid. In this paper, a numerical study has been made to enhance the efficiency and improve the performance of solar collector via the use of (Multi-Wall Carbon Nano Tube-water) MWCNT-H2O nanofluid instead of traditional fluid like water as working fluid under the weather of Mosul city / Iraq (36.3489° N, 43.1577° E). One dimensional dynamic model using implicit finite difference method was used. Solving energy conservation equations through the various layers of the solar system is the basis upon which the current model was based. Effects of nanoparticle volume fraction and mass flow rate on the working fluid stream temperature differences, and the thermal efficiency were studied. The mass flow rate was varied from 0.004 kg/s to 0.03 kg/s, while the volume fraction was varied from 0% to 6%. The results of "Nanofluid Based Flat Plate Solar Collector" were compared with the experimental results presented by [1]. The comparison established a good match between the current results and experimental results. The results showed an increase in the working fluid outlet and inlet temperature difference and collector thermal efficiency due to the addition of MWCNT nanoparticles. The temperature difference of

The solar air heater is a simple device which captures solar energy. Producing hot air by using a solar air heater is a renewable energy heating technology used to process heat generation for space heating. Such systems produce heat at a minimum initial and running cost. Minimum maintenance like cleaning of collectors only is required. Many studies have studied the possibility of improving the performance of solar collectors and raising their thermal efficiency through additions and improvements that were added to the solar heater. Among these improvements are: Adding the extended surfaces to the upper or lower channels, or both, attaching baffles to the absorber plate surface, using corrugated absorber plate, and storing the extra thermal energy and releasing it during sunset. The objective of the present paper is to review the various studies dealing with previous improvements, to present the design modifications, in addition to summarizing their most important results. Based on the review, it is found that: Adding the fins and baffles together to the absorber plate surface of the single or double pass solar air heater has a great effect on improving the thermal efficiency. The use of a corrugated absorber plate leads to a significant increase in the efficiency of the solar air heater. The heat stored in the solar air heater can be used to produce useful heat for several hours after the absence of solar radiation and raise daily efficiency.

The current paper presents an experimental work that had been implemented to observe the performance of an improved solar air heater and compared it with that of a conventional double-pass flat plate solar air heater. Improvements that have been added include the use of a V-shaped corrugated plate at an angle of 60 degrees, the addition of wood baffles in the lower pass and the use of phase-changing materials PCM as well as air recycling conditions. The heater was designed and tested under the weather conditions prevailing in the Duhok Governorate (latitude 36° 52 ' 1.52" N and longitude 42° 59' 18.42" E) in the Kurdistan Region of Iraq. The phase-changing material PCM is paraffin wax. The gathered results showed that the improvements that were added to the solar air heater significantly improved the performance at different mass flow values (0.037, 0.057, 0.077 kg/sec). For example, the maximum values of useful heat transfer at mass flow rates (0.037, 0.057, and 0.077kg/s) are 1.68, 1.86, and 2.34 kW, respectively, and the daily efficiency for improving and conventional heater value at mass flow rate 0.037kg/s for 15,16, and 17 of February on 2022 was (84% and 45%), (86% and 46%), and (91% and 60%), respectively.