ملخص البحث :

A modified version of a three dimensional computer program FLUENT (6.3.26) was used to simulate the complex flow inside the room. The present computational program was validated by comparing the numerical results with experimental data of other study, This comparison show a good agreement. Two main cases were studied with respect to the number of heat sources which were:- 1. Case I: Includes ventilated room with single heat source and one person. 2. Case II: Includes ventilated room with double heat sources and two persons. The effect of ventilation rate corresponding to supply velocities (0.25–0.35 m/s) which is recommended by ASHRAE 2007, supply air temperatures (17 & 19oC) and exhaust grille location on the thermal comfort were investigated based on air distribution performance index (ADPI) in the room. For case I with a heat source of (50 W/m2) heat rejected, the ventilation rate is equal to (6.84 ACH), and supply air temperature of (19 oC) is needed to give better thermal comfort with ADPI equal to 83.6%. For case II with double heat sources each with (50 W/m2) heat rejected, (8.30 ACH) ventilation rate and supply air temperature of (19oC) were needed to get ADPI equal to 83.6%.

ملخص البحث :

A two dimensional turbulence (SST, k- ) model is used to predict the distribution of air velocity and temperature in a 2-D office room, containing one person and office furniture for two ventilation conditions. This study use a commercial CFD code FLUENT (version 6.3) for solving the Navier Stocks, energy and turbulence equations using finite volume techniques. The results were presented as velocity vectors with quantitative velocity and temperature distribution. The result can be divided into two parts, First part compared with published result and gives good theoretical agreement, the second part was taken at boundary conditions (Vin, Tin and Twall) according to the Iraqi environmental condition depend on the Iraqi cods of cooling 2012

ملخص البحث :

Solar water heaters are a prevalent technology for utilizing renewable solar energy, providing hot water for residential and commercial use. Despite their benefits, their efficiency is often hindered by environmental factors such as intermittent sunshine, heat losses, and periods of low solar radiation. The primary challenge addressed in this study is the fluctuating efficiency of solar water heaters due to these environmental constraints. This paper aims to enhance the efficiency of solar water heaters through the integration of phase change materials (PCMs). PCMs are known for their ability to store and release latent heat, potentially stabilizing the heat output of solar water heaters. We employed numerical simulations to investigate the impact of incorporating various PCMs into a flat plate solar collector design. The study focused on determining the optimal properties, structure, and placement of PCMs within the collector to maximize heat storage and transfer. This approach was complemented by experimental validation to confirm the simulation results and assess real-world applicability. The research revealed that suitable PCMs can significantly boost the efficiency and heat retention of solar collectors, particularly during low radiation periods and after sunset. The optimal PCM configuration was found to maintain higher water temperatures for extended periods, thus prolonging the effectiveness of solar water heating into the evening hours. These findings offer valuable insights into the use of PCMs in enhancing the performance of solar thermal technologies, presenting a viable solution to the efficiency challenges faced by current solar water heating systems.