A numerical analysis presented out to simulate internal forced convection and temperature distribution in helical coil tube with and without nanofluid. An ANSYS FLUENT package 14.1 commercial copy with SOLID WORK and GAMBIT software program is employed. The flow pattern and temperature distribution in helical coil tube heat exchanger is studied with and without nanofluid. Numerical work included two parts: the first is included helical coil heat exchanger with optimum curvature ratio (17). An optimum helical coil pitch has been used to study the temperature distribution and flow pattern difference along the turns without nanofluid. The second part included studying the effect of using (Oxide Titanium TiO2) nanoparticle powder with 20 nm diameter dispersed in distilled water with 0.6 % volume concentrations on the same above variables. Temperature contours showed that the temperature decreased along the coil. Also there is difference in temperature between turns. After turn nine the difference become less. The results showed enhancement in the heat flow for fluid with nanofluid compared to without nanofluid.

The present study involves experimental and computational analysis to investigate the thermal performance of modified closed wet cooling tower in perspective of first and second law of thermodynamics (analysis of energy and exergy) according to Iraqi weather. The experimental study includes design, manufacture and testing prototype of a modified counter flow forced draft closed wet cooling tower. The modification based on addition packing to the conventional closed wet cooling tower. To assess the thermal performance of cooling towera progression of tests was done at various operational and conformational parameters.The theoretical study included developed six models by an Adaptive Neuro-Fuzzy Inference System to anticipating various execution parameters of the tower including the cooling range, tower approach, thermal efficiency, cooling capacity, evaporation losses and exergy destruction. After simulating, three dimensional surface viewers obtained for future behavior of the thermal performance of cooling tower involves interactions between all operational parameters. Comparison of the output values obtained using the Adaptive Neuro-Fuzzy Inference System model and those obtained experimentally for other cases not included in the training data, indicates high compatibility with maximum percentage error of (5%).

Abstract:The purpose of the present experimental work is to investigate the performance (1 ton) refrigeration system using nano-refrigerant. Nano-refrigerant is alumina (ɣ-Al 2 O 3 ) nanopartcal with size (20-30) nm is dispersed into R-134a with volume fraction 0.01% and 0.02%. The experimental test rig consists of horizontal double tube counter flow heat exchanger fabricated of copper. The nano-refrigerant is evaporated inside the inner tube because of the heat gain from hot water passing in the annulus surrounding the inner tube. The experimental results indicate, when increasing the volume concentration of Al 2 O 3 refrigerant by 0.01% and 0.02%, the heat transfer coefficient increases by 0.54% to 1.1%. The thermal conductivity increases by 11.5% and 14.2%, respectively, while the coefficient of performance increases by 3.33% to 12%, respectively. The heat transfer rate in the refrigeration side is enhancement about 6.7% to 21.4% compared with conventional refrigerant, and the power consumption by compressor is decreased by nearly 1.6% and 3.3%, respectively.

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