Jet-refrigeration cycles seem to provide an interesting solution to the increasing interest in environment protection and the need for energy saving due to their low plant costs, reliability and possibility to use water as operating fluid. A steam/steam ejector cycle refrigerator is investigated introducing a two-stage ejector with annular primary at the second stage. The steady_state refrigera...

An important issue in the design of systems using borehole heat exchangers is to find costeffective methods to construct the borehole heat exchanger so that heat can be injected or extracted from the ground without excessive temperature differences between the heat carrier fluid and the surrounding ground. This paper presents an overview of experiences and current activities in this field.

Shell and Tube heat exchangers are the heat exchangers that are most widely used in industries and for other commercial purposes. There are many techniques that have been utilized to enhance the heat transfer performance of the shell and tube heat exchangers. Air bubble injection is one of the promising and inexpensive techniques that can create turbulence in the fluids resulting in to enhancem...

Abstract: In this paper a simplified two-dimensional computational model for studying the entropy generation characteristics of thermoacoustic heat exchangers with plane fins is presented. The model integrates the equations of the standard linear thermoacoustic theory into an energy balance-based numerical calculus scheme. Relevant computation results are the spatial distribution of the time-av...

Small minimum temperature approach, large surface area per volume, high heat transfer efficiency and possibility of handling several streams of multi-stream plate-fin heat exchangers lead to more heat recovery and smaller heat exchanger size. Therefore, plate-fin heat exchangers have been applied extensively in sub-ambient processes. However, one major difficulty in optimising the design of pla...

The performance of some commonly used heat exchangers has been investigated with particular reference to the effect of varying the water flow. The results demonstrate that there is considerable variation in the performance of most units when the water flow is changed. It is suggested that more information should be provided by the manufacturers of heat exchangers and that there should be a supp...

A heat exchanger network (HEN) for the process of methanol synthesis has been studied by combination of pinch design method and the application of “Twisted Tube” heat exchanger units as a new technology. The HEN is reconstructed based on the full utilization of maximum allowable pressure drops for the process hot and cold streams. An algorithm is developed to generate design procedure for twist...

The use of natural convection, side-arm heat exchangers in solar domestic water heating systems is becoming a popular method of reducing system cost and electric demand. In this paper, we compare thermal performances of three natural convection heat exchangers mounted along the outside of the water storage tank and a commercial wraparound-tank heat exchanger to two forced-flow heat exchangers. ...

With distributed power generation market, the most economical solution today is to generate power through small gas turbine systems, arbitrarily categorized as microturbines (5 – 200 kW) and miniturbines (200 – 500 kW). The thermal efficiency of such microturbines is about 20% or less if no recuperator is used in the system. Using a recuperator (regenerator can also be considered but has a numb...