Helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. In this kind of heat exchangers, flowand heat transfer are complicated. This paper reports a numerical investigation of theinfluence of different parameters such as coil...

Title of Dissertation: HEAT TRANSFER AND MECHANICAL DESIGN ANALYSIS OF SUPERCRITICAL GAS COOLING PROCESS OF CO2 IN MICROCHANNELS Guohua Kuang, Doctor of Philosophy, 2006 Directed By: Professor Michael Ohadi, Department of Mechanical Engineering Professor Balakumar Balachandran (Co-Advisor), Department of Mechanical Engineering An extensive review of the literature indicates a lack of systematic...

Heat exchangers play significant role in refrigeration and air conditioning systems. Ongoing research aims to improve, or at least maintain, the system performance while reducing the size, weight and cost of the heat exchangers. This in turn leads to lower system refrigerant charge and reduced environmental impact. Using heat exchangers with small tube diameters (less than 5 mm) instead of larg...

objectives the aim of this study was to study the incremental cost-effectiveness ratio associated with the use of heat and moisture exchangers (hme) filter to prevent vap compared with the heated humidifiers (hh) presently adopted by intensive care unit (icu) services within the brazilian healthcare unified system. patients and methods this study was a cost-effectiveness analysis (cea) comparin...

Heat pipes, as two-phase heat transfer devices with extremely high effective thermal conductivity. They can be cylindrical or planar in structure. Heat pipes can be embedded in a metal cooling plate, which is attached to the heat source, and can also be assembled with fin stack for fluid heat transfer. Due to the high heat transport capacity, heat exchangers with heat pipes have become much sma...

This paper is devoted to study the effects of pressure drop in heat exchangers on the dynamics of a free piston Stirling engine. First, the dynamic equations governing the pistons as well as the gas pressure equations for hot and cold spaces of the engine are extracted. Then, by substituting the obtained pressure equations into the dynamic relationships the final nonlinear dynamic equations gov...

In many industrial processes, heat exchangers play the important role of the cooling function. The effective heat transfer rate in a specific process strongly depends on the heat exchanger design. The most popular type of heat exchangers commonly used in the automotive industry, is called "radiator". In engines, radiators play the important role of the cooling process. The present study is de...

Fouling of heat exchangers is a severe problem in the industrialized world. The effects of fouling are reduced energy efficiency and increased greenhouse gas emissions. In fact, any heat transfer process has a risk of fouling on the heat transfer surface. The fouling can in some cases be cleaned physically, chemically or burned off; in other cases it may not be possible to clean the heat exchan...

The effect of γ-Al2O3 nanoparticles on heat transfer rate, baffle spacing and pressure drop in the shell side of small shell and tube heat exchangers was investigated numerically under turbulent regime. γ-Al2O3-water nanofluids and pure water were used in the shell side and the tube side of heat exchangers, respectively. Since the properties of γ-Al2O3-water nanofluids were variable, they were ...

The forced convection heat transfer in high porosity metal-foam filled tube heat exchangers are studied in this paper. The Brinkman Darcy momentum model and two energy equations for both solid and fluid phases in porous media are employed .The study shows that using metal-foams can significantly improve the heat transfer in heat exchangers. Keywords—metal foam, Nusselt number, heat exchanger, h...