Tulin Bali

Experimental investigation of propeller type swirl generator for a circular pipe flow

Abstract The objective of this paper is to introduce the subject of heat transfer augmentation by inserting a propeller type swirl generator in a circular pipe. The propeller type swirl generator creates a flow pattern which is like a decaying swirl flow. This flow pattern is observed for laminar flow. The main advantage of this type of swirl generator is that it is easy to install the device into a circular pipe. Average and local Nusselt numbers were calculated by the method explained in detail in the main text. Comparison of the local Nusselt numbers for swirl flow considered in this study and local Nusselt numbers for flow in a smooth pipe revealed that the local Nusselt number increases substantially when the swirl generator is used. The swirl related heat transfer enhancement becomes stronger as Reynolds number increases.

Modelling of heat transfer and fluid flow for decaying swirl flow in a circular pipe

The economic benefits of energy and material savings have prompted and received greatest attention in order to increase convective heat transfer rates in the process equipment. In the present study, a propeller type swirl generator was developed, and its effects on heat transfer and fluid flow were investigated numerically and experimentally for air flow in a pipe. In the numerical study, for axisymmetrically, incompressible turbulent swirl flows, the Navier-Stokes equations were solved using the {kappa}-{var_epsilon} turbulent model. So that a computer program in Fortran was constructed using the SIMPLEC Algorithm. In experimental work, axial and tangential velocity distributions behind the swirl generator were measured by using hot-wire anemometry. Experimental and numerical axial and tangential velocity distributions along the pipe were compared, and good agreement was found. Axial velocity profile showed a decrement in the central portion of the pipe and an increased axial velocity was seen in near the wall. Tangential velocity profiles had a maximum value and its location moved in radially with distance. The effects of swirl flow on the heat transfer and pressure drop were also investigated experimentally.

Exergy analysis of heat transfer in a turbulent pipe flow by a decaying swirl generator

In this study, heat-transfer and pressure-drop characteristics of a decaying swirl flow in a horizontal pipe are investigated experimentally. The decaying swirl flow is produced by the insertion of swirl generators with propeller-type geometry, a kind of passive heat enhancement tools. Three different positions of the swirl generator in the axial direction are examined: at the inlet (x = 0), x = L/4 and x = L/2. For each position, the effects of the vane angle about the core of the insert device and the number of vanes attached circumferentially to the device on heat transfer and pressure drop are studied. Experiments are conducted at Reynolds numbers ranging from 5000 to 30,000. The optimum geometry is determined according to the exergy analysis and the performance evaluation method used.

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...

Design and Economic Analysis of Photovoltaic Systems in Different Cities of Turkey

In this paper, the production of electrical energy from photovoltaic systems (PV) was studied. Design, comparison, and economic analysis of the systems were performed. In order to carry out system designs and determine the technical and economical parameters of each system, HOMER program was used in the analysis. Belen (Hatay), Gelibolu (Canakkale), Konya, Sinop, Kirklareli, and Karaman cities were selected as the design areas in Turkey. The system and levelized costs of energy were investigated for a load of 2500 kWh case annually, and the effect of capacity shortage fraction on the systems was examined. The systems were designed as grid-connected and off-grid (stand-alone) systems. Grid-connected systems were examined for cases with feed-in tariff. The levelized costs of energy vary between 0.267 and 0.367

An experimental analysis of illumination intensity and temperature dependency of photovoltaic cell parameters

/kWh for PV in the case of feed-in tariff. According to the obtained results, it is determined that the grid-connected systems are more cost effective than stand-alone systems.