Faez Abid Musslem Abd Ali Abd Ali

In the present work, an experimental study has been carried out to investigate a method to reduce the water tank temperature and used it in room air condition. The tests were conducted in the hot season (July and August) in Iraq. The results proved that the device succeeded in reducing the water tank temperature to 23℃, which is a low temperature in the summer and kept at this value by continuous work of the device. It was almost constant at the hot afternoon compared to the temperature of the uncooled tank, which reached its temperature at 2:00 pm to about 43℃ and the difference was 46.5%. The dry air temperature of the test room is very close to the temperature of the house room air (30-33) ℃, compared to the ambient temperature (45-50) ℃. Decrease in the relative humidity to (51-45) % for the test room compared with house room (94-90) %. The power consumption of the system is lower than traditional air evaporative cooler in a rate of 67%.

This numerical analysis is performed to investigate the performance of mixed convection in a vertically oriented air-cooled square cavity. One inlet/outlet placement configuration, when both the inlet and the outlet ports are located at the same bottom side, is considered. The numerical approach is based on the finite volume method integrated in an in-house formulated FORTRAN code to computationally solve the twodimensional Naiver Stock and energy equations with corresponding boundary conditions. The effect of aiding buoyancy on the flow field in a vertical downward laminar jet is examined for Richardson number (0 ≤ Ri ≤ 5) and Reynolds number (25 ≤ Re ≤ 100), with constant physical properties. The results indicate that the increase in Reynolds number increases significantly the average Nussle number; however, the increase in Richardson number slightly affect the amount of heat removal from the cavity. The fundamental nature of the resulting interaction between the buoyancy driven flow and the forced external flow demonstrated by the patterns of the streamlines and isotherms. Importantly, it is found that the placement configuration considered provides unfavorable flow and thermal distributions, and is not beneficial for heat elimination, for most of Reynolds and Richardson values.

Numerical investigation was performed to investigate the convection heat transfer in a square cavity that have been vented vertically. Different values of Reynolds number used (50, 100, 200, and 250) with three different opening to side length ratio (S/L) in the cavity (0.1, 0.2, and 0.3). Richardson number varied between (1, 5, and 10). Galerkin finite element utilized for the numerical simulations, the numerical model was validated and the result obtained was acceptable. The results showed that as Reynolds number increase inside the cavity, the Nusselt number is also increased. From the inlet opening of the cavity to the exit, Nusselt number seamed to decrease. Increasing the value of Richardson number at the same value of Reynolds number increases the Nusselt number within the cavity. Streamlines patterns and isothermal patterns were also shown for the mixed convection flow inside the cavity.

In the present work, experimental and theoretical study has been carried out to investigate the effect of using heat thermosyphon on the performance of cooling photovoltaic thermal solar panel

This paper represents an experimental investigation of cooling the photovoltaic panel by using heat pipe.

of a CPVT (concentrated photovoltaic thermal) system. The CPVT system was tested using a single-axis solar tracking mechanism and a parabolic solar collector that concentrated solar radiation onto a photovoltaic thermal (PVT) module. The cooling system utilized water, and two different geometries—one without VGs and one with VGs—were tested across various flow rates to assess their influence on system performance. The CPVT system consisted of eight monocrystalline solar modules interconnected in parallel to maximize energy collection. The experiments were conducted in Najaf, Iraq, on July 27, 28, 30, 31, and August 2, 2023. Data collection was carried out at 20-min intervals from 10:20 to 14:00 on each test day. Environmental conditions were carefully monitored and recorded using precise measurement instruments. Key performance indicators, such as electrical and thermal efficiencies, were analyzed at various times throughout the day. The results revealed that enhancing the cooling of the solar cells significantly improved their power production capabilities and longevity. Given Iraq’s hot climate, where temperatures can reach extreme levels, effective cooling is crucial to prevent long-term damage to the solar cells. The study found that increasing the coolant flow rate led to a significant improvement in thermal efficiency, with an average enhancement of 22.07 %. The introduction of VGs resulted in substantial gains, with average thermal efficiency increasing by 15 % and electrical efficiency by 23 %. The overall efficiencies of the CPVT systems were recorded as 64.31 % without VGs and 74.81 % with VGs, highlighting a marked improvement in performance due to the incorporation of VGs. This study emphasizes the critical role of effective thermal management in CPVT systems, particularly in hot climates, where the risk of thermal degradation is high.

The compact sizing and lightweight characteristics of thermoelectric devices have garnered significant attention, leading to their widespread use across varied fields. This study experimentally investigates the application of thermoelectric refrigeration in air conditioning, employing a moderately designed system. A unique, multi-U shaped heat sink system was developed, wherein thermoelectric devices were affixed onto rectangular tubes befitting their dimensions, thereby facilitating water as an auxiliary medium for energy transfer. This design enabled the transformation of cold water from the system's cold side to the indoor unit's water-air heat exchanger, while hot water was directed to the outdoor evaporative cooling tank. A Peltier-type thermoelectric device was harnessed for this experiment. The devised setup was subjected to multiple tests to evaluate its thermal performance under the climate conditions of Najaf. Preliminary results validated the effectiveness of the water cooling methodology, with the water temperature observed to decrease to 14℃. Consequently, the room air was cooled by the water-air heat exchanger, reaching temperatures between 20℃ and 24℃. This study underscores the potential of integrating thermoelectric devices with innovative heat sink designs for efficient room air cooling.

With the development of solar energy collection technologies and the mechanism of exploiting solar energy as renewable energy, it was necessary to develop a solar vacuum tube system, which is considered one of the old systems with little efficiency. In order for the development process to be completed, it was necessary to place side reflectors that border the pipes from all sides to better reflect solar radiation and raise the temperature of the pipes to the required level. The optimal angle for increasing temperature was determined by adjusting the sidewalls of mirrors, adjusting the wall width, and comparing angles at various angles (30, 40, 50, 60, 70, 80, 90) degrees, to achieve the best results. The angle of the mirrors on the pipes is adjusted from 30 to 90 degrees, as well as their width from 250 mm to 500 mm, and from 5 a.m. to 5 p.m., with a difference of one hour each reading. The temperature gradient on solar collector tubes increases with time and mirror angle, reaching maximum at noon and 30 degrees. Infrastructural radiation increases significantly at 30 degrees, reaching 700 W/m2. The width of the mirror wall affects radiation reflection and distribution, with a 500 mm width being more effective. The 30-degree angle had the highest thermal efficiency at 84%, while a 500 mm width difference achieved 86%. The novelty of the work varies in terms of developing the thermal efficiency of the solar collector by adding these influential factors to it.

New configuration of concentrated photovoltaic thermal (CPVT) with the implementation of parabolic concentrator and heat sink combined with the vortex generator (VG) were presented in current work. The testing fluid is water and temperature-dependent features were utilized. The regime of water flow in absence and presence of VG are laminar and turbulent, respectively. Numerical simulations were done for different values of angle of VG (θ = 30◦, and 60◦), pitch ratio (S = 0.025, 0.0375, and 0.05), and volumetric flow rate (Q = 0.5, to 2 Lit/min). Four values for width of reflector have been applied and radiation model was utilized to derive the absorbed heat flux. The accuracy of modeling has been examined for three cases and good accommodations have been reported. The maximum values of thermal (ηth) and electrical (ηel) performance are 63.75 % and 13.96 % which happens when θ = 30◦, S = 0.025, Q = 2 Lit/min. Installing VG leads to increments of ηth and ηel about 1.42 % and 2.74 %. Increase of S and θ cause performance to decrease while this function increases with rise of Q. Increase of Q causes ηth and ηel to increase about 1.17 % and 2.55 % for the best case.