Showing papers on "Concentric tube heat exchanger published in 2011"
TL;DR: In this paper, turbulent forced convection flow of water-Al2O3 nanofluid in a circular tube, subjected to a constant and uniform heat flux at the wall, is numerically analyzed.
240 citations
TL;DR: In this article, the authors investigated the effect of helically corrugated tubes on convective heat transfer in a single-phase turbulent flow by using them in a concentric tube heat exchanger.
212 citations
TL;DR: In this article, a three-dimensional analysis is used to study the heat transfer characteristics of a double-tube helical heat exchangers using nanofluids under laminar flow conditions.
154 citations
TL;DR: In this paper, forced convection flows of nanofluids consisting of water with TiO2 and Al2O3 nanoparticles in a horizontal tube with constant wall temperature are investigated numerically.
144 citations
TL;DR: In this paper, an experimental investigation was carried out to study mixed convection of Al 2 O 3 -water nanofluid inside an inclined copper tube submitted to a uniform wall heat flux at its outer surface.
97 citations
TL;DR: In this article, an experimental and theoretical investigation of the utilization of finned tube compact heat exchanger for a heat recovery steam generator (HRSG) to recover both sensible and latent heat is presented.
95 citations
TL;DR: In this paper, a three dimensional computational fluid dynamics simulation was carried out to understand the effect of simultaneous variation of design parameters, and two functions for the total heat transfer efficiency and the heat exchanger efficiency were derived.
95 citations
TL;DR: In this article, the authors used double-sided delta wings (T-W) as vortex generators for enhancing the heat transfer coefficient by breakdown of thermal boundary layer and by mixing of fluid flow in tubes.
90 citations
TL;DR: In this paper, the air-side pressure drop and heat transfer performance of plate-fin and micro-channel coils were tested under clean and fouled conditions, and the results showed that the ASHRAE Standard Dust was found to have a very significant impact on the pressure drop of the microchannel heat exchanger.
82 citations
TL;DR: In this article, the heat transfer coefficient of HFO-1234yf inside a smooth small-diameter horizontal tube (inner diameter: 2 mm) was experimentally investigated.
Abstract: The flow boiling heat transfer coefficient of the low-GWP (global warming potential) refrigerant HFO-1234yf inside a smooth small-diameter horizontal tube (inner diameter: 2 mm) was experimentally investigated. The local heat transfer coefficient was measured at heat fluxes of 6–24 kW m -2 , mass fluxes of 100–400 kg m -2 s -1 , evaporating temperature of 288.15 K, and inlet vapor quality of 0–0.25. The results show that the effect of heat flux on the heat transfer was large at low vapor quality, while the effect of mass flux was large at high vapor quality. The heat transfer coefficient of HFO-1234yf was almost the same as that of R-134a. The heat transfer coefficients calculated based on correlations with Saitoh et al. agreed well with the measured values compared to other correlations. The measured pressure drop agreed well with that predicted by the Lockhart-Martinelli correlation.
81 citations
TL;DR: In this article, a 3D numerical simulation is performed on laminar heat transfer and flow characteristics of a slit fin-and-tube heat exchanger with longitudinal vortex generators, and the structure of the slit fin is optimized and analyzed with field synergy principle.
TL;DR: In this article, the plate and concentric tube heat exchangers are tested by using the water-water and nanofluid-water streams, and the experimental results show that the heat transfer rate and heat transfer coefficients of the nanofluid in both of the heat exchanger is higher than that of the base liquid (i.e. water) and the efficiency of plate heat exchange is higher.
Abstract: The plate and concentric tube heat exchangers are tested by using the water-water and nanofluid-water streams. The ZnO/water (0.5 v/v%) nanofluid has been used as the hot stream. The heat transfer rate omitted of hot stream and overall heat transfer coefficients in both heat exchangers are measured as a function of hot and cold streams mass flow rates. The experimental results show that the heat transfer rate and heat transfer coefficients of the nanofluid in both of the heat exchangers is higher than that of the base liquid (i. e. water) and the efficiency of plate heat exchange is higher than concentric tube heat exchanger. In the plate heat exchanger the heat transfer coefficient of nanofluid at
TL;DR: In this article, a spiral-coil tube is fabricated by bending a 8.00-mm diameter straight copper tube into a spiral coil of five turns, and the innermost and outermost diameters of the spiral coil are 270.00 and 406.00 millimeters, respectively.
TL;DR: In this paper, an experimental investigation of the hydrodynamic and thermal fields in a two-channel chevron-type plate heat exchanger for laminar and turbulent conditions is presented.
TL;DR: In this article, the air-side performance of crimped spiral fin and tube heat exchangers at high Reynolds number (3000-13,000) was investigated, and no significant effect for either number of tube rows or fin materials on the heat transfer performance was found.
TL;DR: In this article, the authors presented the flow boiling heat transfer characteristics of R134a in the multiport minichannel heat exchanger and compared the results of two test sections with different the number of channels.
TL;DR: In this article, a comparison of experimental data and numerical predictions for the hydrodynamic and thermal fields in a two-channel plate heat exchanger is presented, where the temperature distributions on the first and the last of the three plates, the friction factor and the Nusselt number for each channel as well as the outlet temperatures of the two streams are compared.
TL;DR: In this paper, the performance analysis of a finned U-shape heat pipe used for desktop PC-CPU cooling is presented by mounting the system vertically over a heat source situated inside a rectangular tunnel, and force convection is facilitated by means of a blower.
TL;DR: In this paper, the authors present the condensation heat transfer and flow characteristics of R-134a flowing through corrugated tubes experimentally, which is a horizontal counterflow concentric tube-in-tube heat exchanger 2000mm in length.
TL;DR: In this paper, a numerical investigation of the mixed convection heat transfer from vertical helically coiled tubes in a cylindrical shell at various Reynolds and Rayleigh numbers, various coil-to-tube diameter ratios and non-dimensional coil pitches was carried out.
Abstract: A numerical investigation of the mixed convection heat transfer from vertical helically coiled tubes in a cylindrical shell at various Reynolds and Rayleigh numbers, various coil-to-tube diameter ratios and non-dimensional coil pitches was carried out. The particular difference in this study compared with other similar studies is the boundary conditions for the helical coil. Most studies focus on constant wall temperature or constant heat flux, whereas in this study it was a fluid-to-fluid heat exchanger. The purpose of this article is to assess the influence of the tube diameter, coil pitch and shell-side mass flow rate on shell-side heat transfer coefficient of the heat exchanger. Different characteristic lengths were used in the Nusselt number calculations to determine which length best fits the data and finally it has been shown that the normalized length of the shell-side of the heat exchanger reasonably demonstrates the desired relation. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, the optimal design of a multi-pass plate-and-frame heat exchanger with mixed grouping of plates is considered, including the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, and the plate type and size.
TL;DR: In this paper, the authors examined the airside performance of the wavy fin-and-tube heat exchangers having a larger diameter tube (Dc = 16.59mm) with the tube row ranging from 1 to 16.
TL;DR: In this paper, an electronic ice thickness measurement method is used to monitor the solid-liquid interface variations during phase change and this method is validated by the comparison of visual and temperature data.
TL;DR: The experimental results pertaining to nanofluid efficiency seemed inauspicious and the overall heat transfer coefficient for 6 vol% Al2O3 increased to 30% because at the given viscosity and density of the nan ofluids, they did not have the same flow rates.
Abstract: In this paper, the heat transfer characteristics and pressure drop of the ZnO and Al2O3 nanofluids in a plate heat exchanger were studied. The experimental conditions were 100-500 Reynolds number and the respective volumetric flow rates. The working temperature of the heat exchanger was within 20-40 degrees C. The measured thermophysical properties, such as thermal conductivity and kinematic viscosity, were applied to the calculation of the convective heat transfer coefficient of the plate heat exchanger employing the ZnO and Al2O3 nanofluids made through a two-step method. According to the Reynolds number, the overall heat transfer coefficient for 6 vol% Al2O3 increased to 30% because at the given viscosity and density of the nanofluids, they did not have the same flow rates. At a given volumetric flow rate, however, the performance did not improve. After the nanofluids were placed in the plate heat exchanger, the experimental results pertaining to nanofluid efficiency seemed inauspicious.
TL;DR: In this article, the authors derived the governing equations based on the conceptual model in the cylindrical coordinate system and solved them using the finite volume approach, using SIMPLE algorithm on the collocated arrangement.
TL;DR: In this article, a horizontal counter-flow concentric tube-in-tube heat exchanger with R-134a flowing in the inner tube and hot water flowing in an annulus Smooth tube and corrugated tubes with inner diameters of 87mm and lengths of 2000mm were used as the inner tubes.
TL;DR: In this paper, the authors investigated the comparison of the heat transfer and pressure drop of the microchannel and minichannel heat exchangers, both numerically and experimentally, and concluded that the micro-channel heat exchanger should be selected for the systems where high heat transfer rates are needed.
Abstract: The present study investigated the comparisons of the heat transfer and pressure drop of the microchannel and minichannel heat exchangers, both numerically and experimentally. The results obtained from this study indicated that the heat transfer rate obtained from microchannel heat exchanger was higher than those obtained from the minichannel heat exchangers; however, the pressure drops obtained from the microchannel heat exchanger were also higher than those obtained from the minichannel heat exchangers. As a result, the microchannel heat exchanger should be selected for the systems where high heat transfer rates are needed. In addition, at the same average velocity of water in the channels used in this study, the effectiveness obtained from the microchannel heat exchanger was 1.2–1.53 times of that obtained from the minichannel heat exchanger. Furthermore, the results obtained from the experiments were in good agreement with those obtained from the design theory and the numerical analyses.
TL;DR: In this article, the effects of nanoparticle volume fraction on the hydrodynamics and thermal parameters are presented and discussed at different Richardson numbers, it is shown that increasing the nanoparticle concentration significantly augments the heat transfer coefficient while the skin friction coefficient does not considerably affect.
TL;DR: In this paper, the effect of step height on heat transfer to a radially outward expanded air flow stream in a concentric annular passage was studied experimentally and the results show good agreement with previous works and have followed similar trends.
TL;DR: In this paper, the effect of structural parameters on heat transfer characteristic of conical spiral tube was discussed. And the results showed that the cone angle and cross section have significant effect on tube heat transfer, while the helical pitch has little influence on tube's heat transfer enhancement.