Teoman Ayhan

Neural network methodology for heat transfer enhancement data

Purpose – The purpose of this paper is to study experimentally enhancement of heat transfer in a tube with axial swirling‐flow promoters. The geometric features of flow geometry to improve heat transfer can be selected in order to yield the maximum opposite reduction in heat exchange flow irreversibility by using exergy‐destruction method. The paper seeks to illustrate the use of neural network approach to analyze heat transfer enhancement data for further study in the scope of the experimental program.Design/methodology/approach – For this purpose, 402 experimental measurements are collected. About 225 of those are used as training data for neural networks, the rest is used for testing. Then, these testing results of artificial neural network (ANN) and experimental data are compared. A formula for presenting exergy loses in a tubular heat exchanger is derived first and then the thermodynamic optimum instead of economic optimum is found by minimizing the exergy losses in the system.Findings – Results from...

Experimental Investigation and Computational Fluid Dynamics Analysis of Flow and Heat Transfer for Heated Plate

This study investigated the characteristics of convective heat transfer and fluid flow for a heated plate surrounded by unheated plates aligned at angles to the flow direction inside a rectangular ...

Combined effects of evaporation and cavitation on the performance of a renewable energy powered natural vacuum desalination unit in Bahrain

AbstractThe renewable energy powered natural vacuum desalination unit (NVDU) presents a promising alternative technique for seawater desalination and wastewater treatment, with low energy consumption, simple technology, and resulting clean environment. The problem of the low daily productivity of the NVDU motivated researchers to investigate various means of improving its productivity and thermal efficiency in order to reduce the production cost of freshwater. This study investigates experimentally the performance of the NVDU under the combined effects of evaporation and cavitation on freshwater production rate. The NVDU consists of an inverse U-shaped pipe, with one side acting as the evaporator and the other side as the condenser. The experiments were conducted under three different sets of conditions. The first had ambient conditions on both sides, the second used a water-ring vacuum pump to create a buoyancy effect, and the third was similar to the second set of conditions, but with cooling of the con...

Effects of Intake Air Cooling Performance Improvement on a Two-Shaft Laboratory-Scale Gas Turbine Unit

The present study deals with the thermodynamically modelled two-shaft gas turbine system consisting of a cooling unit at the compressor inlet. The system is used to investigate the generated power, thermal efficiency and second law efficiency. The parametric study using this model shows effect of ambient conditions, compressor inlet temperature, and pressure ratios on power output, thermal efficiency and second law efficiency. Theoretical results using the proposed model show that when the compressor inlet temperature is decreased by some kind of cooling systems, the net power output and thermal efficiency increases up to 30% and 23%, respectively. Also, the second law efficiency of the proposed system increases in compression to the specified reference state. It shows that the proposed model is thermodynamically viable. A comparison of the performance test results of the model and the experimental results are in good agreement. The results provide valuable information regarding the gas turbine system and will be useful for designers.Copyright