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.

Optimum design of Heat Exchanger networks is an important subject in process design practice. Scientists and researchers have put a lot of effort to develop new methodologies for design and optimization of such networks, using both mathematical and conceptual approaches. In conventional pinch analysis, as a conceptual approach, an initial network is first synthesized using pinch design method, and then optimized by implementation of appropriate rules and techniques. However, these rules and techniques do not involve pressure drop considerations. In a recent research, new optimization methodology has been developed that includes three stages, each of which comprises many algorithms. The first stage of this methodology, which focuses on Heat load optimization, is explained in this article. The method of Heat load optimization in this paper is based on this loop breaking rules and techniques, and at the same time makes use of mathematical programming to find optimum point. Due to the differences between the nature of grass-root and retrofit projects, different procedures have been developed accordingly. These new procedures have also been applied to two case studies (Aromatics as grass-root, and crude distillation unit, as retrofit) and the results proved to be as expected.Having optimized the two initial networks, 4 percent improvement in total annual cost of aromatics network and 6.5 percent improvement in investment or 11 percent improvement in payback of the CDU network were identified.

De sediment of Heat Exchanger is common in industry and lot s of efforts have been done. In this article (essay) it has been studied about decreasing of sediment on-line way and its advantage in compare to off-line way. and also if has been studied about ammonia units air compressor problem in petrochemical co in khorasan that is resulted from sediment of Heat Exchanger of third stage , with usage of coloridric asid %5 and flomate matter %2 on line by preventing from stop of ammonia units and also urah units chemical washing of E-2143 Exchanger activity , caused decreasing of compressor vibration ,decreasing of Exchangers waters temperature, decreasing of air outlet air temperature of Exchanger, increasing of cool water flowing and deduction and cost saving, and is finished successfully.

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.

A helical double-pipe Heat Exchanger filled with a porous material under asymmetric Heat flux is studied analytically. Momentum and energy equations are transformed to the Germano? s coordinate and then expressions representing the velocity and temperature fields are obtained based on the powers of dimensionless curvature using perturbation analysis. To be more insightful، contours of velocity and temperature fields are presented. Results reveal an asymmetric axial velocity profile arising from the curved geometry. The Nusselt number increases with respect to the dimensionless curvature increment as well as the inner to outer radius ratio increase.

Heat transfer is one of the most critical processes in the industry, and by increasing the efficiency of the Heat Exchanger, energy consumption of systems will be reduced. Very tiny particles in nanoscale dimensions, when uniformly dispersed and stably suspended in the base fluid, efficiently improve the thermal properties of the base fluid. With the help of nanofluids, the Heat transfer rate increase. The purpose of this research is to investigate the thermal and hydraulic characteristics of nanofluid in turbulent flow regime in a plate Heat Exchanger with a sine pattern in which cold and hot flows alternately pass through the plates. First, problem geometry is modeled and simulated in ANSYS-FLUENT software. All properties of nanoparticles are dependent on temperature, velocity, and particles diameter, and are added to software in the form of a separate code. Simulations are for different parameters such as wavelength to amplitude ratio (L/A), Reynolds number, volume fractions of nanoparticles and nanoparticle diameter. The results indicate that the best shape of the wave for the highest Heat transfer rate in the Heat Exchanger is gained for equal wave amplitude and wave length.

An experimental database is compiled in order to fingerprint the scales formed over the hot surfaces of Heat Exchangers, in cooling water systems or other systems with similar chemistry. To collect these data, a dynamic simulating pilot plant was designed with considerable application flexibility among which simultaneous flow of water with different velocity and Heat fluxes to three simulating Heat Exchangers can be mentioned. Changing the water chemistry and using various inhibitors composition known in the art, the nature of scale deposits formed on the Heating elements was studied by scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray instrument. The Heat flux of the elements ranges from 9.46×104 to 1.45×105 J/m2. sec, which depending on the velocity of fluid passing through the orifice of pipe, give rise to skin temperatures of 80°C to 230°C. The flow velocities used in this study were 0.21 and 0.46 m/sec. Phosphonates and most popular polymers were studied as scale inhibitors.

In the initial steps of grass-root projects, Heat Exchangers cost estimation for proper decision making regarding network optimization design through pinch technology is very important. It is necessary to forecast the cost of a Heat Exchanger through cost estimation equations. In this article, the cost estimation equations of Heat Exchanger and the Heat Exchangers network for shell and tube Heat Exchangers and plate and frame Heat Exchangers are obtained. These equations are the function of Heat transfer area by available prices in Iran. The proposed relations for Shell and tube Heat Exchangers are in the maximum operating pressure region of shell and tube side between 1.22-41 bars and made of two types of material: carbon steel and stainless steel 3116. Furthermore, plate and frame Heat Exchangers relations in two regions of the inlet cold flow lower than 30 cubic meters and between 30 to 500 cubic meters are obtained. These plate and frame Heat Exchangers are made of stainless steel 316. Moreover, here the proposed equations is studied.

In this study a Plate-Fin Heat Exchanger (PFHE) with offset-strip fins has been optimized on air-air, water-water and air-water working fluids types. In the first step - designing the PFHE - the Heat transfer and pressure drop analyses were done. Considering the geometrical parameters of fins (pitch, height and offset length of fins) and the relationship of the amount of Heat transfer and pressure drops with the velocity of working fluids in each types, the volume of PFHE and its total annual cost based on the allowable pressure drop on both sides as the constraints were calculated. Then, Genetic Algorithm (GA) was used for searching and optimization of the structure sizes of the PFHE considering pressure drop constraints. Comparing the current results with the literature shows that the volume of optimized PFHE for all three types decreases from 10 to 15% and the total annual cost declines from 5 to 25%.