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The experimental process carried out in this paper is to determine the convection heat transfer coefficient, overall heat transfer coefficient, and nanofluid heat transfer rate based on DWCNT (double-wall carbon nanotube) nanotubes applied to a shell and tube heat exchanger. The advantage of using DWCNT nanoparticles is the high thermal conductivity value. The volume fractions of nanoparticles were 0.1%, 0.3%, and 0.5% with the addition of PVP surfactant. Experimental tests were conducted to determine the heat transfer performance applied to a shell and tube type heat exchanger with upright baffles. This study aims to improve the heat transfer performance by utilizing nanofluids based on DWCNTs nanoparticles. As a result, using DWCNT nanofluids instead of base fluids increases the convective heat transfer coefficient values and overall heat transfer. The increase in the volume fraction of DWCNTs nanoparticles is also accompanied by an increase in the heat generated. The highest thermal conductivity was obtained by adding 0.5% volume of DWCNTs nanoparticles, which was 0.640 W/m.K. The highest heat transfer rate was produced by adding 0.5% volume fraction and 0.02% PVP with a result value of 70.191 W. [ABSTRACT FROM AUTHOR]

The experimental process is carried out in this paper to determine the value of the convection heat transfer coefficient, overall heat transfer coefficient, and the rate of heat transfer for nanofluids based on DWCNTs (double-wall carbon nanotubes) nanoparticles which ar e applied to shell and tube heat exchangers. The advantage of using DWCNTs nanoparticles is the high thermal conductivity value. The volume fractions of nanoparticles were 0.1%, 0.3%, and 0.5%. Tests were carried out to determine the heat transfer performance applied to the shell and tube type of baffle and no-baffle heat exchanger tools. The purpose of this research is to improve the heat transfer performance by utilizing nanofluids based on DWCNT nanoparticles. The results show an increase in the value of the convection heat transfer coefficient and the overall heat transfer coefficient when using DWCNTs nanofluids rather than using base fluids. [ABSTRACT FROM AUTHOR]

As with the development of heat exchangers, especially in the fields of energy and microelectronics, where the mini-channel used in heat exchanger operations is used, as increasing the efficiency of heat exchangers depends on transferring the largest amount of heat to and from the used band. To increase this transfer, obstacles must be used to improve heat transfer, as these barriers disturb the used fluid and increase heat transfer by convection. In this research paper, a mini-channel containing obstacles of variable thickness was used to study the extent of their effect on heat transfer and its strength to withstand the flow pressures in the mini-channel and prevent its deformation. The results proved that with the increase in the thickness of the obstacle, it increases its strength to withstand stresses but at the same time reduces its strength in convective heat transfer. The reason for this is that the increase in the thickness of the obstacle increases the area for heat transfer and thus increases the resistance and heat and prevents heat transfer significantly. [ABSTRACT FROM AUTHOR]

Nanofluid is a novel industrial fluid that has the potential to improve heat exchanger performance. This paper presents an experimental study on the forced convective heat transfer of a graphene oxide nanofluid composed of water/Ethylene glycol and various volume percentages of GO nanofluid (0.5–2) percent passing in a cylindrical shell and tube heat exchanger with various baffle angles. Counter flow is investigated in turbulent flow conditions. The influence of heat transfer rate, entropy development, and overall heat transfer coefficient in heat exchangers with various baffle angles. The above-stated factors of the heat exchanger were governed by conventional correlations using nanofluids. Among the different reformed baffle angles, cylindrical shape nanoparticles performed best in factors of heat transfer rate and overall heat transfer coefficient. The overall heat transfer coefficient of cylindrical shape particles with 120 baffle angle is found to be 15%, 24%, and 30% higher than 240, 360baffle angles, in consistent to 1.5 vol. percent of GO nanofluid. Heat transfer is also found to be greater for cylindrical shapes at 120baffle angle than for other baffle angles. Entropy development, on the other hand, decreases with increasing volume percentage for all baffle angles. [ABSTRACT FROM AUTHOR]

The paper provides the reducing method efficiency assessment of the heat losses into the environment due to the heat losses supply to the heat carrier flow, previously flowing through the additional water jacket including the subsequent heated heat carrier flow direction into the heat-exchanging unit main flow part. Accordingly, the main heat carrier is notionally considered as the «active» insulation. The theoretical comparative analysis of this type of insulation efficiency with regard to the modes typical for the MCU recovery systems was conducted. The study was carried out by means of the numerical method through the heat transfer processes modelling of the system «heat carrier -- wall -- hot gas -- wall -- heat carrier - environment», i.e. in the recuperative heat exchanger possible design simplified version. Thus, the comparative study and analysis subject is the design consisting in the first case of two coaxial tubes, between which the hot gas flows (internal combustion engine exhaust gases) and water flows through the axial channel, while in the second case -- of three coaxial tubes with the main heat carrier (water) flowing through the axial and external circular channels. In the second case, the water mass flow rate of the external circular and internal cylindrical channels is the same. The heat transfer processes calculation analysis was conducted on the basis of the convective heat transfer, thermal conductivity and radiation heat transfer known equations implemented in the ANSYS software. [ABSTRACT FROM AUTHOR]

The paper presents data on the heat exchange extended surfaces application and convective and radiative heat exchange intensification. One of the most effective methods of heat transfer intensifying is using the regularly positioned ridges (corrugated surface) in the pipe, which provide heat exchange area increasing and are the turbulent excitations generation sources additionally to the already existing natural excitations in the flow. The use of the ellipse cross section with the cross corrugation makes it possible to improve the furnace heat reception intensity by more than 5-5.5% as compared to the furnace with the ellipse cross section and smooth inner surface. [ABSTRACT FROM AUTHOR]

Innovative design of perforated and non-perforated fin is a prime importance of thermal system to enhance the rate of heat transfer. The traditional and innovative designs of fins used in different applications such as IC engines, heat exchangers, electronics heat sinks, electric motors, etc. The main aim of this article is to present a comprehensive review on the comparative thermal performance analysis between solid and perforated fins. Also focused on heat transfer analysis of different types of fins with various designs and dimensions, also studied free and forced convection heat transfer with correlations of dimensionless numbers. Researchers emphasized that the rate of heat transfer of perforated fins is greater than the conventional fins. The review concluded with recommendations that recently developed perforated fins are the best choice than solid fins for enhancing the heat transfer rate of thermal systems. Also the concept of perforated fins can be applied to an electric motor/machine in order to enhance the heat transfer rate and ultimately its life and efficiency. [ABSTRACT FROM AUTHOR]

The simulation studies are made to understand the concept of heat transfer by convection in a rectangular coiled type heat exchanger. The rectangular coil heat exchanger consists of inner and outer coil arrangements with several straight portions and bends so that the exterior flow is very similar to flow within tube-bundles. The present work focuses mainly on exploring the various flow pattern and temperature distribution through the pipe. Computer simulation studies were performed for four different angle of tube bundle inclination (0°, 30°, 60°, and 90°) with two set flow arrangements (inline and staggered arrangement) in the shell side of the heat exchanger. The simulation results show that the effect of the tube bundle inclination on the fluid velocity distribution and the heat transfer performance is observed maximum for the coil with tube bundle inclination angle between 30 degrees and 60 degrees with the staggered arrangement than with the inline arrangement due to proper mixing in the shell side and the outside flow over the tube bundle helps to create turbulence without increasing the velocity in the shell side of the heat exchanger. [ABSTRACT FROM AUTHOR]