scholarly journals Thermal Performance of an Energy Pile Group with a Deeply Penetrating U-Shaped Heat Exchanger

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5822
Author(s):  
Weidong Lyu ◽  
Hefu Pu ◽  
Jiannan (Nick) Chen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Pile Group ◽  
Cooling Mode ◽  
Energy Pile ◽  
Pile Spacing ◽  
Pile Diameter

This study presents a novel heat exchanger configuration, called a deeply penetrating U-shaped configuration, for energy piles. The outlet water temperature, temperature variation along the tube, and heat transfer rate are simulated and computed using Comsol Multiphysics software. The simulations are for the cooling mode. The proposed configuration is compared with traditional U-shaped and W-shaped configurations to prove its superiority. The thermal performance of the pile group is compared with that of a single pile to investigate the effects of the pile group on the heat transfer. A parametric analysis is performed to investigate the effects of several important parameters (i.e., pile spacing, pile diameter, soil type, and thermal parameters) on the heat transfer performance of an energy pile group with the proposed deeply penetrating U-shaped configuration. The results indicate that the corner pile indicates a nonnegligible heat transfer rate 6.8% and 9.9% higher than the central pile in quincuncial and squared arrangements. Purely from the standpoint of thermal performance, the pile spacing is recommended to be more than 6.8 times the pile diameter to reduce the influence of the pile group on the heat transfer capacity.

Performance Evaluation of Tube-in-Tube Heat Exchanger Using Nanofluids

2015 ◽  
Vol 787 ◽  
pp. 72-76 ◽  
Author(s):  
V. Naveen Prabhu ◽  
M. Suresh
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Element Analysis ◽  
Tube Heat Exchanger

Nanofluids are fluids containing nanometer-sized particles of metals, oxides, carbides, nitrides, or nanotubes. They exhibit enhanced thermal performance when used in a heat exchanger as heat transfer fluids. Alumina (Al2O3) is the most commonly used nanoparticle due to its enhanced thermal conductivity. The work presented here, deals with numerical simulations performed in a tube-in-tube heat exchanger to study and compare flow characteristics and thermal performance of a tube-in-tube heat exchanger using water and Al2O3/water nanofluid. A local element-by-element analysis utilizing e-NTU method is employed for simulating the heat exchanger. Profiles of hot and cooling fluid temperatures, pressure drop, heat transfer rate along the length of the heat exchanger are studied. Results show that heat exchanger with nanofluid gives improved heat transfer rate when compared with water. However, the pressure drop is more, which puts a limit on the operating conditions.

scholarly journals Thermal Characteristics of Slinky-Coil Ground Heat Exchanger with Discrete Double Inclined Ribs

Resources ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 105
Author(s):  
Teguh Hady Ariwibowo ◽  
Akio Miyara
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Ground Heat Exchanger ◽  
Average Heat ◽  
Thermal Mixing

The slinky ground heat exchanger (GHE) is the most widely utilized horizontal-type GHE, however, this GHE has a low curvature coil. The GHE has poor thermal mixing, especially at a low flowrate. At this flowrate, the coil heat exchanger has similar performance to a straight tube heat exchanger. Discrete double-inclined ribs (DDIR) are well known for their good thermal mixing by generating a vortex in straight tubes. In this paper, a numerical analysis of thermal performance for the plain coil and DDIR coil is discussed. It was found that the thermal performance of the DDIR coil was slightly higher than that of the plain coil in laminar flow. In turbulent flow, the DDIR coil was superior to the plain coil only in the first 149-min operation. The first 60-min analysis shows that in laminar flow, the average heat transfer rate in the plain coil is 59 W/m and in the DDIR coil is 60.1 W/m. In turbulent flow, the average heat transfer rate is 62 W/m, and the plain coil is 62.3 W/m. The copper DDIR coil material produced a better heat transfer rate than that of the composite and High-Density Polyethylene (HDPE). Sandy clay has the highest heat transfer rate. The influence of ground thermal conductivity on the performance of the GHE is more dominant than convection in the DDIR coil.

scholarly journals Implementation of a Neural Network Tool for Evaluation of Thermal Performance in a Heat Exchanger by using Double Elliptical Leaf Angle Strips with same Orientation and Same Direction

2019 ◽  
Vol 8 (6) ◽  
pp. 4325-4332
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Leaf Angle ◽  
Generalized Regression Neural Network ◽  
Double Pipe

Exchange of energy in all processes generally occur in the form of heat & work. The exchange of heat is determined by the rate of heat exchange between hot and cold body or cold and hot body. To exchange this heat we need two energy stacks such as a source & sink. So, whenever heat is rejected or accepted the energy change occurs identically i.e. amount of heat rejected is equal to amount of heat gained in an ideal case but when heat transfer rate is analyzed it is different fsor different processes such as vaporization is an instantaneous process whereas the condensation is slower and takes much more time so, with this idea that heat transfer rate can be altered individually in different processes an idea of analyzing heat exchanger by introducing elliptic double shaped leaf strips within the double pipe heat exchanger and the rate of heat transfer and pressure drop in is planned at various orientations of angles . From these obtained results neural network tool was designed for evaluating the thermal performance named the generalized regression neural network (GRNN).In this process certain input parameters are given (temperatures, mass flow rate) and instantly predefined output parameters (heat transfer rate, pressure drop) are obtained.

scholarly journals Numerical analysis of thermal performance of heat exchanger: Different plate structures and fluids

2021 ◽  
pp. 195-195
Author(s):  
Muhammad Khan ◽  
Yong Song ◽  
Qunying Huang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Low Cost ◽  
Working Fluid ◽  
Modular Construction ◽  
Construction Time ◽  
Compact Size

Due to compact size, high power density, low cost and short construction time, the Small Modular Reactors (SMRs) are considered as one of the candidate reactors, in which the power generation system is important with a compact heat exchanger for modular construction. Therefore, the effect of plate structure and nature of the working fluid on the thermal performance of Plate Heat Exchanger (PHE) are analyzed for the design of compact and efficient heat exchanger. The heat transfer rate, temperature counters, velocity vectors and pressure drop have been optimized and investigated using FLUENT. The Nusselt number has been calculated for the corrugated and flat PHE to validate the convective heat transfer. The numerical results are agreed well with correlation within deviation of ~ 5-7%. The performance of heat exchanger can be improved by controlling the mass flow rate and temperature of working fluid. The corrugation PHE increases the heat transfer rate 20 % and effectiveness 23 %, respectively, as compare to flat PHE when the working fluid is water. In the case of air, heat transfer rate and effectiveness are about 10 % and 9 %, respectively. The results show that the corrugated PHE is more effective than the flat PHE because corrugation pattern enhances the turbulence of fluids, which further increase heat transfer rate and coefficient. The selection of the working fluid and structure of the plate must be considered carefully for efficient and compact design of heat exchanger.

Thermal Performance Assessment of Turbulent Flow Through Dimpled Tubes

2010 ◽  
Author(s):  
Pornchai Nivesrangsan ◽  
Somsak Pethkool ◽  
Kwanchai Nanan ◽  
Monsak Pimsarn ◽  
Smith Eiamsa-ard
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Staggered Arrangement ◽  
Plain Tube ◽  
Pitch Ratio ◽  
Surface Patterns

This paper presents the heat transfer augmentation and friction factor characteristics by means of dimpled tubes. The experiments were conducted using the dimpled tubes with two different dimpled-surface patterns including aligned arrangement (A-A) and staggered arrangement (S-A), each with two pitch ratios (PR = p/Di = 0.6 and 1.0), for Reynolds number ranging from 9800 to 67,000. The experimental results achieved from the dimpled tubes are compared with those obtained from the plain tube. Evidently, the dimpled tubes with both arrangements offer higher heat transfer rates compared to the plain tube and the dimpled tube with staggered arrangement shows an advantage on the basis of heat transfer enhancement over the dimpled tube with aligned arrangement. The increase in heat transfer rate with reducing pitch ratio is due to the higher turbulent intensity imparted to the flow between the dimple surfaces. The mean heat transfer rate offered by the dimpled tube with staggered arrangement (S-A) at the lowest pitch ratio (PR = 0.6), is higher than those provided by the plain tube and the dimpled tube with aligned arrangement (A-A) at the same PR by around 127% and 8%, respectively. The empirical correlations developed in terms of pitch ratio (PR), Prandtl number (Pr) and Reynolds number, are fitted the experimental data within ±8% and ±2% for Nusselt number (Nu) and friction factor (f), respectively. In addition, the thermal performance factors under an equal pumping power constraint of the dimple tubes for both dimpled-surface arrangements are also determined.

Experimental Study on Compact External Heat Exchanger for a 4 MWth Circulating Fluidized Bed Combustor

2013 ◽  
Vol 448-453 ◽  
pp. 3259-3269
Author(s):  
Zhi Wei Li ◽  
Hong Zhou He ◽  
Huang Huang Zhuang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling Water ◽  
External Heat ◽  
Circulating Ash ◽  
Fluidized Bed Combustor ◽  
External Heat Exchanger

The characteristics of the external heat exchanger (EHE) for a 4 MWth circulation fluidized bed combustor were studied in the present paper. The length, width and height of EHE were 1.5 m, 0.8 m and 9 m, respectively. The circulating ash flow passing the heating surface bed could be controlled by adjusting the fluidizing air flow and the heating transferred from the circulating ash to the cooling water. The ash flow rate passing through the heat transfer bed was from 0.4 to 2.2 kg/s. The ash average temperature was from 500 to 750 °C. And the heat transfer rate between the ash and the cooling water was between 150 and 300 W/(m2·°C). The relationships among the circulating ash temperature, the heat transfer, heat transfer rate, the heat transfer coefficient and the circulating ash flow passing through the heating exchange cell were also presented and could be used for further commercial EHE design.

scholarly journals Improvement on the Calculation of Heat Transfer Rate for a New Type of Geothermal Energy Pile

IFCEE 2021 ◽  
2021 ◽  
Author(s):  
Yong Zou ◽  
Jie Huang ◽  
Fei Wang ◽  
John S. McCartney ◽  
Elahe Jafari
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Geothermal Energy ◽  
Transfer Rate ◽  
Energy Pile ◽  
New Type

OPTIMIZATION OF HEAT TRANSFER RATE ON A DOUBLE PIPE HEAT EXCHANGER USING CFD

2021 ◽  
Vol 34 (02) ◽  
Author(s):  
Mohammad Sikindar Baba ◽  
◽  
Oddarapu Kalyani ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Double Pipe ◽  
Pipe Heat

Experimental Investigation on Thermal Performance of Heat Sink With Two Pairs of Embedded Heat Pipes

2007 ◽  
Author(s):  
Hsiang-Sheng Huang ◽  
Jung-Chang Wang ◽  
Sih-Li Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Heat Sink ◽  
Transfer Rate ◽  
Heat Pipes ◽  
Total Heat ◽  
Heating Power ◽  
Total Heat Transfer

This article provides an experimental method to study the thermal performance of a heat sink with two pairs (outer and inner pair) of embedded heat pipes. The proposed method can determine the heat transfer rate of the heat pipes under various heating power of the heat source. A comprehensive thermal resistance network of the heat sink is also developed. The network estimates the thermal resistances of the heat sink by applying the thermal performance test result. The results show that the outer and inner pairs of heat pipes carries 21% and 27% of the total heat transfer rate respectively, while 52% of the heating power is dissipated from the base plate to the fins. The dominated thermal resistance of the heat sink is the base to heat pipes resistance which is strongly affected by the thermal performance of the heat pipes. The total thermal resistance of the heat sink shows the lowest value, 0.23°C/W, while the total heat transfer rate of the heat sink is 140W and the heat transfer rate of the outer and inner pairs of heat pipes is 30W and 38 W, respectively.

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