A numerical and experimental investigation of flow and HEAT transfer in a gas- liquid THERMOSYPHON HEAT EXCHANGER "THE" with built in HEAT pipes and aluminum plate fins for moderate Reynolds numbers has been carried out. It's module is composed of 6 rows and 15 columns copper pipes with aluminum plate fins with dimensions of 130cm height, 47cm width and 20cm depth. The tubes have been filled with water with filling ratios of 30%, 50% and 70%. The density and thickness of fins are 300 fin/m and 0.4 mm, respectively. The configuration of tubes is in-line with 30mm pitch. This paper presents the distribution of temperature and thermal performance of "THE" by using CFD modeling. A good comparison of the present CFD modeling results for the modeling THERMOSYPHON HEAT EXCHANGER with experimental results of hydrodynamic and thermal behavior is achieved.

Waste HEAT recovery is very important, because it not only reduces the expenditure of HEAT generation, but also it is of high priority in environmental consideration, such as reduction in greenhouse gases. One of the devices used in waste HEAT recovery is HEAT pipe HEAT EXCHANGER. An experimental and theoretical research is carried out to investigate HEAT performance of an air to water THERMOSYPHON HEAT pipe HEAT EXCHANGER according to e-NTU method. The experiments were done according to the following procedure: cold water with 0.1kg/s flows through the condensation section and hot air in a closed cycle is blown into the evaporation section. A blower with varying frequency of current turns in the mass flow rate between 0.14-0.6 kg/s and a temperature range of 125-225°C. The results of the experiments show that as the ratio of Ch/Cc rises, the rate of HEAT transfer goes up. The efficiency of the HEAT pipe HEAT EXCHANGER remains constant as the temperature of the hot stream goes up, but the amount of HEAT transferred increases.

Waste HEAT recovery is very important, because not only it reduces the expenditure of HEAT generation, but also it is of high priority in environmental consideration, such as reduction in greenhouse gases. One of the devices is used in waste HEAT recovery is HEAT pipe HEAT EXCHANGER. An experimental research has been carried out to investigate the hydrodynamic and thermal performance of a gas- liquid THERMOSYPHON HEAT EXCHANGER “THE” in a pilot plant. The e-NTU method has been used. The pressure drop has been calculated across tube bundle of the THERMOSYPHON HEAT EXCHANGER. It's module is composed of 6 “rows” and 15 “columns” copper pipes with aluminum plate fins with dimensions of 130 cm “height”, 47 cm “width” and  20 cm “depth” . The tubes have been filled by water with filling ratio of 30 %, 50 % and 70 %. The density and thickness of fins are 300 fin/m and 0.4 mm, respectively. The configuration of tubes is in-line with 30 mm pitch. The results show that as the ratio of Ce/Cc raises the amount of HEAT transfer increases. The effectiveness of HEAT pipe HEAT EXCHANGER remains constant as the temperature of hot stream rises, but the amount of HEAT transfer increases. Filling ratio in normal region (30-70 %) has no effects on experimental results. A new correlation for THERMOSYPHON HEAT EXCHANGER with individual finned tubes and in-line geometry has been proposed for calculating pressure drop across tube bank of a “THE”. The error in pressure drop for 40 experimental points in the new correlation is less than 15 %. This indicates that the new correlation possesses an acceptable accuracy predicting pressure drop.

Conservation of energy by waste HEAT recovery is important not only for cost reasons, but also for reducing primary energy consumption as well as reducing carbon dioxide production. This paper explains and discusses the simulation, performance, and successful applications of THERMOSYPHON HEAT EXCHANGERs (THE’s) for recovering waste HEAT from exhaust gases in industrial plants. The advantages of this system are compactness, flexibility of system size, ease of operation, and minimum maintenance requirements. The THERMOSYPHON HEAT EXCHANGER can satisfactorily act as a pre-HEATer of air in boilers and furnaces using the HEAT recovered from the exhaust. In this work, one successful industrial practice is explained using THERMOSYPHON HEAT EXCHANGER. The THE was simulated to recover waste HEAT from the exhaust of a nearly 7 ton boiler in the SAMEN company. The energy recovered from the flue gas is used to preHEAT the incoming air to the boiler. The average rate of waste HEAT recovery and thermal effectiveness obtained from computer simulation are 100 kW and 40%, respectively. The payback period was less than two years. The evaluation of the thermal performance of the THE was based on the effectiveness-NTU and LMTD methods to obtain the HEAT transfer characteristics.

HEAT EXCHANGERs are widely used in power engineering and industrial applications. Many techniques such as coiled tube, surface tension devices, rough surfaces and extended surfaces have been investigated to enhancethermal performance and minimize the cost and size of the HEAT EXCHANGER equipment. One of the most important techniques is tube insert. In general, tube inserts can be classified into two broad categories: stationary inserts and self-rotating inserts. Compared with stationary inserts, the self-rotating inserts can rotate in the tube by fluid and the comprehensive performance of self-rotating inserts is improved significantly. This paper mainly focuses on reviewing the large number of experimental and numerical works taken by researchers on self-rotating inserts such as twisted tapes, miniature hydraulic turbine, turbine-type swirl generators, etc. To improve the thermal efficiency of HEAT EXCHANGER and serviceable to designers implemention of passive enhancement techniques in HEAT EXCHANGER are required. The authors found that self-rotating inserts can streng then the HEAT transfer efficiency, meanwhile achieve on-line automatic anti-scaling and descaling effect. When the fluid velocity is more than 0.2m/s, most of self-rotating inserts can be applied. The HEAT transfer performance and frictional loss have been discussed to get the optimal configuration of self-rotating inserts. The convective HEAT transfer correlations have also been discussed. Determining how to find the optimal self-rotating insert is the main objective of this paper.

This paper investigates optimization methods based on genetic algorithms (GAs) for spiral HEAT EXCHANGERs. The purpose of designing HEAT EXCHANGER depends on its application and could be total cost, HEAT transfer coefficient or both of them. The current targeting methods identify optimum points from both economic and thermodynamic views and capture a trade-off between two objectives. Optimizations using single objective functions are performed in order to investigate parameter behavior in two different applications of SHEs. Also this work takes care of numerous geometric parameters in the presence of logical constraints. Multi-objective and weighted function optimizations using genetic algorithm are developed in order to obtain a set of geometric design parameters, which lead to minimum pressure drop and the maximum overall HEAT transfer coefficient. Optimized HEAT transfer coefficient compared to its first value at basic design had a 13% increase and total cost in optimized case presents 50% reduction compared to the basic design. Also in trade-off cases, HEAT transfer coefficient and total cost have been improved up to 60% increment and 20% reduction respectively. Therefore, designing HEAT EXCHANGER using presented optimal methods in this research are proposed as useful methods for designers, engineers and researchers.