Laminar natural convection heat transfer and fluid flow due to the heating from below at variable heat source length inside two dimensional enclosure has been analyzed numerically in this study. The enclosure has filled with air as a working fluid. The vertical inclined walls of the enclosure are maintained at lower temperature while the remaining walls are insulated. The value of Rayleigh number from (1x103 ≤ Ra ≤ 4x104), the inclination angle at (γ = 0o, 22.5o , 45o ) and dimensionless heat source length at ( S = 1 and 0.5 ). The continuity, momentum and energy equations have been applied to the enclosure and solved by using finite difference method. The results showing that the average Nusselt number increases with the increasing of the heating source length and decreases with the increasing in an inclination angle of the vertical walls.
An experimental study is achieved to study the thermal performance of forced unglazed solar air collector supplied with perforated absorber flat plate. The study is carried under Iraqi circumferences in Al-Ramadi city .The collector is inclined (90o) on horizontal for the simplicity of setting such type of collector on the wall building and minimize its weight. The measurement is recorded on Winter season for two sunny days and two cloudy days in (January 2012). The results show that its possible to use this type of collectors for heating in Winter time because the maximum out air temperature reach to (34oC) when ambient air temperature at (17oC) in sunny days. A good agreement is shown with the published studies Finally its obtained a good effectiveness for perforated flat plate absorber with high system efficiency.
Reducing energy consumption and to ensure thermal comfort are two important considerations in designing an air conditioning system. The control strategy proposed is fuzzy logic controller (FLC).This paper describes the development of an algorithm for air condition control system based on fuzzy logic (FL) to provide the conditions necessary for comfort living inside a building.Simulation of the controlling air conditioning system, on which the strategy is adopted, was carried out based on MATLAB This system consists of two sensors for feedback control: one to monitor temperature and another one to monitor humidity. The controller i.e. FLC was developed to control the compressor motor speed and fan speed in order to maintain the room temperature at or close to the setpoint temperature.
A steam boiler is a metal vessel in which a particular liquid is heated to steam. Steam is used in the production of energy in several areas as most boilers convert water to steam used in heating buildings and others. Steam boilers are exposed to corrosion and sediment as a result of salts dissolved in water, which may lead to increased temperature inside the boiler and thus the boiler explosion. The research included finding a suitable way to solve the problem of sedi-ment and corrosion by adding suitable chemicals to get rid of the dissolved salts inside the water and maintain steam boiler. To control this problem, the control system is designed to control the amount of salts in the water in the steam boiler using PLC.
A solar water heating system has been fabricated and tested to analyze the thermal performance of Parabolic Trough Solar Collector (PTSC) using twisted tape insert inside absorber tube with twisted ratio about TR=y/w=1.33. The performance of PTSC system was evaluated by using three main important indicators: water outlet temperature (Tout), useful energy and thermal efficiency (ηth) under the effect of mass flow rate (ṁ) ranges between 0.02 and 0.04 Kg/s with the corresponding of Reynolds number (Re) range (2000 to 4000). In a parallel, a fuzzy-logic model was proposed to predict the thermal efficiency (ηth) and Nusselt number (Nu) of PTSC depending on the experimental results. The fuzzy model consists of five input and two output parameters. The input parameters include: solar intensity (I), receiver temperature (Tr), water inlet temperature (Tin), water outlet temperature (Tout) and water mass flow ( ) while, the output include the thermal efficiency (ηth) and Nu. The final results indicate that, owing to the mixture of the swirling flow of the perforated twisted-tape insert, the perforated twist tape insert enhances the heat transfer characteristics and the thermal efficiency of the PTSC system. More specifically, the use of perforate twist tape inserts enhanced the thermal efficiency by 4% to 4.5% higher than smooth absorber tube. Also, the predicted values were found to be in close agreement with the experimental counterparts with accuracy of ~92 %. So, the suggested Fuzzy model system would have high validity and precision in forecasting the success of a PTSC system compared to that of the traditional model. Pace, versatility, and the use of expert knowledge for estimation relative to those of the traditional model are the advantages of this approach