Heat exchanger

Heat exchanger, which transfers the heat from one medium to another, is the most common thermal equipment in various of industry sectors. It’s widely used in chemical, energy, machinery, transportation, refrigeration, air conditioning and aerospace fields. Apart from assuring the certain technological processes and necessary conditions, heat exchanger also provides solutions to the heat recovery and energy conservation of the industry secondary energy.

exchangers and (ii) sizing heat exchangers for a particular application. Rating involves determination of the rate of heat transfer, the change in temperature of the two fluids and the pressure drop across the heat exchanger. Sizing involves selection of a specific heat exchanger from those currently available or determining the dimensions for the design of a new heat exchanger, given the required rate of heat transfer and allowable pressure drop. The LMTD method can be readily used when the inlet and outlet temperatures of both the hot and cold fluids are known. When the outlet

system was provided for use in fuel cell vehicles, when considering the heat exchanger arrangements. This cycle which had an inverter-controlled, electricity-driven compressor was applied to the automotive heat pump system for both cooling and heating. The cooling and heating loops consisted a semi-hermetic compressor, supercritical pressure micro channel heat exchangers (a gas cooler and the cabin heater), a micro channel evaporator, an internal heat exchanger, an expansion valve and an accumulator. The performance characteristics of the CO 2 heat pump system for fuel cell vehicles were

Buildings used for housing of animals in farms with intensive breeding, like poultry or pig houses, are characterized by high generation of heat inside, mainly produced by animals, and in the case of young animals, supplemented also by heating. On the other side these buildings need intensive ventilation which causes large losses of energy by exhausted air. A good way to reduce heat losses can be the use of heat recovery technical systems (Kic and Gurdil, 1999; Kic and Pavlicek, 2006a; Kicet al., 2007). Whereas in recuperators, where heat is transferred directly and immediately through a partition wall of some kind, from a hot to a cold fluid, both of which flow simultaneously through the exchanger, the operation of the regenerative heat exchanger involves the

Apart from Tijani’s design by Meghan Labounty and Andrew Lingenfelter (2008), there were other researchers which were Cila Herman and Yuwen Chan (2006) that proposed three designs of heat exchangers suitable for thermoacoustic refrigerators, parallel-strips, finned-tubes and flat-tube-banks heat exchangers as in Figure 2.6. It shows the heat exchanger together with the corresponding portion of the stack plate, viewed perpendicular to the plane of stack plate. They also added that the base will be maintained at a temperature different from the thermoacoustic working fluid. Heat conduction from the middle (resonance tube axis) to the ends of the highly conductive metal strips will rely on the transport of thermal energy in the parallel-strips heat exchanger as shown in Figure 2.6a. The metal strips of the heat exchanger should ideally be aligned with the plates when the stack plates are parallel. However, they added that, eventhough the blockage of acoustic waves caused by the heat exchanger strips in the resonance tube is minimized and acoustic losses are reduced, but the thermal resistance of the heat exchanger strips in this solution is large, because of the heat transfer relying on heat conduction alone along the strips. However, Garrett et al. (1994) suggested that this design was suitable for small thermoacoustic refrigerators with cooling loads under 10 W.

Sheikholeslami et.al (2018) Impact of distinctive and perforated uneven helical turbulators on flow and in transfer of heat in an air to water double pipe heat exchanger are practically analysed. According to the practical facts, relationships among Nusselt number, friction factor and performance of thermal parameter are accessed as functions of distinct constraints. Non-dominated Sorting Genetic Algorithm II is in action to get the maximum high efficiency of designed heat exchanger. Practical steps are being showed to examine flow to be turbulent and transfer of heat in an air to water heat exchanger prepared with usual and perforated intermittent helical turbulators. Impacts of the Reynolds number, ratio of open area and ratio of pitch on loss in pressure and transfer of heat enhancement are observed. Relationships among Darcy factor, Nusselt number and performance of thermal parameters are obtained. Zhouhang Li et.al (2017) Helical coils have gained ever more interest in the area of carbon dioxide of supercritical range with Rankine cycles through the past era due to the dense assembly and great rate of heat transfer. Previous analyses basically concentrated on influence of operational conditions and with the gravitational up thrust, and are not satisfactory to properly comprehend the behavior of supercritical carbon dioxide gas heaters with helically coiled. Impact of few different main elements, such as the alignments of coil and roughness of inner wall, on full enactment that’s been rarely stated and is still uncertain to date. In this work we filled such opening with a solid to fluid conjugate model of heat transfer where supercritical turbulence flow is explained by the Shear Stress Transport k-u functions. Impact of coil alignments and inner rib roughness on transfer of heat of supercritical carbon dioxide which have been inspected in helical coiled tubes with different dimensionless curvature d. Consequences describes that the alignment impact was thoroughly correlated to the effect of gravitational buoyancy.

In order to increase the heat transfer rate of the vapor condensation heat exchanger, the current investigation focused on the condensation heat transfer and forced convection. To increase the heat transfer coefficient, the elliptical pin fins with nanofluid was investigated. The forced convective heat transfer on nanofluids in an elliptical pin-fin heat sink of two different pin orientations was studied by using a finite volume method. With increasing Reynolds number, the recirculation zones behind the pins increased. There were more recirculation zones for the pins with different angular orientations than for pins with the same angular orientation. It was observed that the Nusselt number for the pins with different angular orientations was higher than that for pins with the same angular orientation. The results showed that with increasing volume fraction of nanoparticles and angular orientation of pins for a given Reynolds number, Euler and Nusselt numbers as well as overall heat transfer efficiency increase. By utilizing thin film evaporation in the two-phase flow heat exchanger, investigations were performed for heat flux and pressure distributions. The maximum liquid pressure difference continuously increases with the superheat. The maximum liquid pressure difference peaks at about 5 C superheat. The curvature and interface temperature profiles were different at different superheats. A decrease in temperature occurred when the thin film profile increased in thickness. Both the x and y dimensionless coordinates and superheat at various thin film profiles were viewed and there were two crests in regions  x   4.0, y   0.5  and  x   2.0, y   1.5  , and two shallow troughs in

Tuckerman and Pease [1] first proposed the concept of microchannel heat sinks in 1981. In the comparison with conventional heat exchanger microchannel has a higher heat transfer performance low to moderate pressure drops, smaller geometric size and lower coolant requirement and lower operational cost. Researchers have explained microchannel with different criteria. Some of those are reviewed here. First we discuss microchannel based on the hydraulic diameter of channel. Mehendale et al. [2] described microchannel based on the hydraulic diameter as:

By fouling we mean any accumulation of unwanted material on surfaces of a process equipment hinders the desired operation. This issue is particularly common in food industry, chemical industry and energy industry (including waste-to- energy applications). Overall heat transfer co efficient then falls due to higher thermal resistance of the layer,which implies lower heat exchanger efficiency and in turn , huge economic losses. For example, Hewitt (1998) provided and estimate as large as 1.4 billion USD per year for plants in the United States. It is therefore obvious that fouling must be taken into account when designing any process unit that is expected to work with a fluid having a high fouling propensity. We must eliminate as many stagnation zones with swirling character of flow as possible or atleast minimize formation of eddies. Plan surfaces and suitable materials should be used to further lower fouling rate. Additionally, units should be constructed in such a way that cleaning of heat transfer surfaces and other essential regions is easy.

Ebru Kavak Akpinar et al [1], has studied the effect of heat transfer rates, friction factor and energy loss by applying the holes on the swirl generators. Various numbers of holes having different diameters were used. Hot air and cold water were passed through the inner pipe and annulus, respectively. Experiments were carried out for both parallel and counter flow models of the fluids at Reynolds numbers between 8500–17 500. Heat transfer, friction factor and energy analyses were made by comparing with and without swirl generators conditions. By giving rotation to the air with the help of swirl elements Nusslet number was increased upto130% at a value of about 2.9 times increase in the friction factor. With Swirl generators energy was found to be increased by 1.25 times as compared with that for inner pipe without swirl generators. After performing the experiment for both counter and parallel flow mode, results were compared to those obtained from the empty tube and Dittus–Boelter correlation Nu = 0.023Re0.8Pr0.4 (describes non-swirling flow in the smooth- tube). The highest Nusselt number was achieved with the heat exchanger operated in a counter-flow mode and equipped by a swirl generator having 20 circular holes with 3 mm diameter. While the increase in the Nusselt number was 113% at swirl generator having 20 circular holes with 6 mm diameter, the increase was 109% at 9 mm diameter.

Use of the ITD as the driving temperature difference would give the same result as the LMTD method only if there was no temperature change of the fluid temperature along the flow length. Such would be the case if the heat is rejected to an infinite heat sink (e.g., of the heat sink temperature , which experienced no temperature change. This is typically assumed in “boundary layer flow” over an object for which the heat sink T is a constant. Figure 1a shows this case. However, for “channel flow” shown in Figure 1b, the heat sink fluid temperature changes along the flow length. The Figure 1b situation is typically applied to heat exchanger design, where the fluid temperature changes along and Eq. 4 applies to this situation.

As a compact heat exchanger, plate fin heat exchanger is applied in many industries and occupies a unique role due to its flexible arrangement, simple shape and good thermal effectiveness. Based on different applications, various kinds of fins are used in plate fin heat exchangers, such as plain, offset-strip, louvered, wavy and pin [1-5]. Kays and London conducted an experimental analysis of about 40 kinds of fins and offered the corresponding correlation curves of heat transfer and resistance [6]. Khoshvaght-Aliabadi investigated seven common configurations of channels used in plate fin heat exchangers experimentally. The results showed that vortex-generator channel can be applied as a high quality interrupted surface and wavy channel displayed an optimal performance in low Reynolds numbers [7]. Juan Du carried out experimental and numerical investigation of the heat transfer and pressure drop characteristics of an offset plate fin heat exchangers for cooling of lubricant oil [8]. Numerical simulations and experimental investigation of air flow and heat transfer over wavy fin were presented by Dong. The results show that the waviness amplitude has the distinct effect on the heat transfer and pressure drop of wavy fin [9].

Abstract— A heat exchanger is a device, which transfer internal thermal energy between two or more fluids at different temperature. Without this essential piece of equipment most industrial process would be impossible. Heat exchangers are widely used in refrigeration air conditioning, and chemical plants. They can be employed in various uses, for instance, to effectively transmit heat from one fluid to the other. Shell-and-tube heat exchangers (STHXs) are widely applied in various industrial fields such as petroleum refining, power generation and chemical process, etc. Tremendous efforts have been made to improve the performances on the tube side.In this project experimental performance is done on the fixed designed STHX and calculate the heat transfer coefficient and effectiveness. Validation is to be carried out using which gives the result comparison with that of experimental result.Here flow parameters are not varied but size and number of tubes are varied and best efficient model is selected as Optimized value. 3 different number of tubes are used with same shell size remaining same. 40 tubes , 32 tubes and 36 tubes were tried . It's been observed for same input temperatures and mass flow rates for three different models one with 36 tubes , 32 tubes model &other with 40 tubes, the temperature variation in 36 tubes is more and also requires less tubes compared to 40 tube model. so it is more effective than tubes model.

(NTU). Joao Ramos et al. [10] developed a CFD model for a heat pipe heat exchanger to recover waste heat and results were shown as that the modelling predictions were upto 10% of the experimental results. Hussam Jouhara et al. [11] designed and investigated a flat heat pipe to recover the waste heat from steel industries and results shows a better efficiency. Andrei Buelacu et al. [12] presented a heat transfer analysis which was used to recover waste heat from buildings and use the transfered heat for domestic applications like hot water and heating the room ventilation system with high efficiency and at less cost of manufacturing. Himel Barua et al. [13] investigated the filling ration for water and ethanol and stated that above 50% of filling ratio both the working fluids gives better performance but upto 80 % of filing ratio the performance will be much higher and above that temperature changes does not occur. Hussam Jouhara and Richard Meskimmon [14] proved that wraparound loop heat pipe heat exchanger working with water is efficient than heating, ventilation and air conditioning systems has a raise of about 18% effectiveness which was useful for energy applications. Ojha Pramod Kailash et al. [15] designed a pipe in pipe heat exchanger with higher efficiency for various parameters and varied with the simple inner tube and fin tube heat exchanger. Ravi Kumar Banjare et al. [16] discussed briefly about the materials that are used for heat exchanger also explained the performance of ceramics as material in heat exchanger material. Hossein Kavusi and Davood Toghraie [17] studied the performance of various nanofluids in heat pipe and resuted that the flow from evaporator to condenser section is done by wick material easily with a raise of thermal capacity also when fluid pressure drop is attain a certain level difference of temperature between the evaporator and the condenser increases. Vishal H Acharya [18] reviewed the performance of heat pipe with various parameters with effective flow rate and velocity. Durga Bastakoti et al. [19] Investigated performance of alcohols in heat pipes and resulted that surface tension and viscosity are main factor of performance of the heat pipe in addition with a statement of filling ratio is the first most important factor for the performance. R. Senthil et al. [20] investigated thermal efficiency of heat pipe with Al2O3 working fluid and showed that there was a better result which could be used practically.

In process industries, during operation of any heat exchanger network (HEN), the major aim is to focus on the best performance of the network. Frequently one encounters problems that degrade the HEN performance, like heat exchanger fouling, leakage in tubes, changes in process stream conditions (flow rate, temperature), frequent changes in arrangement of utility streams to optimize heat recovery in the network, shutdown of heat exchangers for maintenance, etc. Since the changes can take place in any of the heat exchangers in the network, a complete analysis of the network in an integrated approach is required (Morgan, 1992 and Rossiter et al., 1993). In order to handle these issues a good understanding of modeling and simulation of HENs in a simultaneous approach is necessary (Smith and Linnhoff, 1988). The simulation software such as CHEMCAD after trying the iterations results in the following optimum parameters which have seems to be good to propose the design. The temperature values mentioned in the streams tables have been further used for the calculation of cold and hot stream data.

I would like to express my deepest appreciation to all those who helped me to complete my final year project and report writing. First of all, I would like to express my special gratitude to my supervisor, DR.Safarudin Gazali Herawan, from the Faculty of Mechanical Engineering University Teknikal Malaysia Melaka (UTeM) who gave me this opportunity to do this project with the title of study on heat exchanger for steam generator from waste heat. I also would like to express my appreciation for his encouragement and patience, for every constructive comment and thoughtful recommendation throughout this study.

water. The present work has been carried out on double pipe heat exchanger for water to water and nanofluid to water heat transfer investigation with counter flow arrangement under turbulent flow condition. The computational fluid dynamic code is used to simulated different concentrations of nanofluid (0.01% to 0.19%) in ANSYS FLUENT 14 software. The overall heat transfer coefficients for all concentrations are measured as a function of hot and cold streams mass flow rates. Considering friction factor, one appropriate concentration (0.1%) is taken into account experimentally. The thermal performance parameter overall heat transfer coefficient is compared for nanofluids with water. The study is done at different mass flow rates and inlet fluid temperatures. It is observed that for high Reynolds number low concentration of nanofluid is useful. The work concludes that there is promising enhancement in heat transfer rate using nanofluid .

Heat exchange between flowing fluids is one of the most important physical process and a variety of heat exchangers are used in different industrial applications, as in process industries, compact heat exchangers nuclear power plant, refrigeration, power plants, chemical processing and food industries, etc. The main purpose of constructing a heat exchanger is to get an efficient method of heat transfer from one fluid to another, by direct contact or by indirect contact. The heat transfer occurs by three modes which are: conduction, convection and radiation. In a heat exchanger, the heat transfer through radiation is not taken into consideration as it is negligible in comparison to conduction and convection. Conduction takes place when the heat from the high temperature fluid flows through the surrounding solid wall. The conductive heat transfer can be enhanced by selecting minimum thickness of wall of a highly conductive material. But convection plays a major role in the performance of a heat exchanger. Helical coil configuration is very effective for heat exchangers because they can accommodate a large heat transfer area in a very small space, with very high heat transfer coefficients.

Abstract- Heat exchangers are the important engineering systems with wide variety of applications including power plants, nuclear reactors, refrigeration and air-conditioning systems, heat recovery systems, chemical processing and food industries. In the present study was to analyze the fluid flow in double pipe heat exchangers and the subsequent performance of these heat exchangers. To facilitate this analysis, the FLUENT 14.5 was used to perform the modeling and calculations. In order to verify the development of each model, the models were built in stages and each stage analyzed and verified. The first stage was a theoretical validation of problem for given specifications and determine the outlet temperatures of hot and cold fluid in parallel and counter flow using NTU method. In the second stage heat exchanger modeling and analysis was carried out. The results show that, good agreement with theoretical values by varying mesh quality and size. After preparing the method in Ansys fluent, the outlet temperatures for different materials and different fluids were determined. Using this outlet temperatures compactness of heat exchanger, entropy generation, exergy loss in a heat exchanger was investigated.

Spiral plate heat exchangers are built by rolling two parallel long sheets around a central bar to make a spiral shape. The free final edges of channels then will weld together to seal the end of channels. The distance between metal sheets is kept using studs that are welded to the sheets. The length of studs can vary from 5 to 25 mm. hence, with respect to the mass flow rate, different distances between the sheets can be chosen during the design period. In each channel, hot or cold fluid path, secondary flows are developed that lead to better mixing and therefore heat transfer rate is increased and fouling is decreased. These heat exchangers are compact but their complicated construction procedure cause higher primary construction costs. Heat transfer surface area of these heat exchangers is from 0.5 to 500 m 2 . Maximum working pressure and temperature often restricted to 15 bar and 450 degrees Celsius, respectively. Applying new technologies may increase the maximum temperature up to 850 degrees Celsius. Using available equations and with respect to experimental requirements, a small LAB- sized model of the heat exchanger was made. Galvanized-Iron sheets were used. Properties of Galvanized-Iron are given in Table 1.