Dynamic Heat Transfer Study of a Triangular-Shaped Latent Heat Storage Unit for the Attic Space of a Domestic Dwelling

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Tonny Tabassum ◽  
Mainul Hasan ◽  
Latifa Begum
Keyword(s):  
Latent Heat ◽  
Wall Temperature ◽  
Tube Wall ◽  
Numerical Study ◽  
Control Volume ◽  
Staggered Grid ◽  
Melting Time ◽  
Efficient Design ◽  
Latent Heat Storage ◽  
Tube Wall Temperature

Abstract A two-dimensional (2D) numerical study is carried out to investigate the thermal performance of an impure phase-change material (PCM) in an equilateral triangular-shaped double pipe heat exchanger. To tackle the irregular boundaries, a nonorthogonal body-fitted coordinate (BFC) transformation technique is employed. The nondimensional transformed curvilinear conservation equations for mass, momentum, and energy are written in terms of physical variables and they are solved using a control-volume based finite difference method on a staggered grid arrangement. The developed model is then used to study the effects of the inner tube wall temperature, the initial temperature of the solid PCM, and the shape, as well as the position of the inner tube in the annulus on the melting characteristics, and cumulatively stored energy. Various quantities such as average Nusselt numbers over the inner tube surface, the total and complete melt fractions, and the latent and total stored energies all as a function of the melting time are reported. A correlation for the average Nusselt number on the inner tube wall is also provided. The numerical results show that the shape and the placement of the inner tube are crucial for the efficient design of a latent heat thermal energy storage (LHTES) system. The storage of energy is greatly influenced by the change of the inner tube wall temperature compared to the change of initial solid PCM temperature.

scholarly journals Effect of Twisted Fin Array in a Triple-Tube Latent Heat Storage System during the Charging Mode

2021 ◽  
Vol 13 (5) ◽  
pp. 2685
Author(s):  
Mohammad Ghalambaz ◽  
Jasim M. Mahdi ◽  
Amirhossein Shafaghat ◽  
Amir Hossein Eisapour ◽  
Obai Younis ◽  
...  
Keyword(s):  
Energy Storage ◽  
Heat Exchanger ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Storage ◽  
Hot Water ◽  
Melting Time ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger ◽  
Storage Rate

This study aims to assess the effect of adding twisted fins in a triple-tube heat exchanger used for latent heat storage compared with using straight fins and no fins. In the proposed heat exchanger, phase change material (PCM) is placed between the middle annulus while hot water is passed in the inner tube and outer annulus in a counter-current direction, as a superior method to melt the PCM and store the thermal energy. The behavior of the system was assessed regarding the liquid fraction and temperature distributions as well as charging time and energy storage rate. The results indicate the advantages of adding twisted fins compared with those of using straight fins. The effect of several twisted fins was also studied to discover its effectiveness on the melting rate. The results demonstrate that deployment of four twisted fins reduced the melting time by 18% compared with using the same number of straight fins, and 25% compared with the no-fins case considering a similar PCM mass. Moreover, the melting time for the case of using four straight fins was 8.3% lower than that compared with the no-fins case. By raising the fins’ number from two to four and six, the heat storage rate rose 14.2% and 25.4%, respectively. This study presents the effects of novel configurations of fins in PCM-based thermal energy storage to deliver innovative products toward commercialization, which can be manufactured with additive manufacturing.

Influence of fin parameters on melting and solidification characteristics of a conical shell and tube latent heat storage unit

2021 ◽  
pp. 1-37
Author(s):  
Lokesh Kalapala ◽  
Jaya Krishna Devanuri
Keyword(s):  
Cylindrical Shell ◽  
Latent Heat ◽  
Conical Shell ◽  
Heat Storage ◽  
Melting Time ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Efficient Operation ◽  
Shell And Tube ◽  
Melting And Solidification

Abstract Augmenting meting and solidification rates of latent heat storage unit (LHSU) is very much essential for its efficient operation. By the effective utilization of natural convection, rate of heat transfer can be enhanced and the conical shell is beneficent in this regard. Employing fins further improves the charging and discharging rates. Hence the current study is focused on analyzing melting and solidification characteristics of a conical shell and tube LHSU along with the effect of fin parameters viz. fin diameter and number of fins. Numerical analysis is chosen for this purpose and the performance is compared via melting/solidification times, energy stored, energy/exergy efficiencies. Initially the performance of unfinned conical shell is compared with the cylindrical shell without fins and then the effect of fin parameters is presented. For melting process conical shell is found to be superior to cylindrical shell. 34.46% reduction in melting time is noted by employing conical shell and rate of energy stored is also higher for conical shell. Increase in fin diameter caused an increase in melting time when 20 number of fins are used, whereas melting time got decreased with the increase in fin diameter when 5 number of fins are used. Hence, when a greater number of fins are employed lesser diameter is preferred for melting. For discharging process, conical shell took 60% more time than cylindrical shell. Even after employing fins, solidification time is not drastically reduced in comparison to cylindrical shell.

scholarly journals Fouling in a Steam Cracker Convection Section Part 1: A Hybrid CFD-1D Model to Obtain Accurate Tube Wall Temperature Profiles

2019 ◽  
Vol 41 (2) ◽  
pp. 127-137 ◽  
Author(s):  
Pieter Verhees ◽  
Abdul Rahman Akhras ◽  
Kevin M. Van Geem ◽  
Geraldine J. Heynderickx
Keyword(s):  
Wall Temperature ◽  
Tube Wall ◽  
Temperature Profiles ◽  
Tube Wall Temperature ◽  
1D Model ◽  
Steam Cracker

scholarly journals NUMERICAL STUDY OF THE GEOMETRIC INFLUENCE OF A FIN IN A CYLINDRICAL HEAT EXCHANGER FOR MELTING OF PCM

2019 ◽  
Vol 18 (1) ◽  
pp. 78
Author(s):  
F. C. Spengler ◽  
B. Oliveira ◽  
R. C. Oliveski ◽  
L. A. O. Rocha
Keyword(s):  
Heat Exchanger ◽  
Aspect Ratio ◽  
Phase Change ◽  
Latent Heat ◽  
Heat Storage ◽  
Numerical Study ◽  
Melting Process ◽  
High Energy ◽  
High Energy Density ◽  
Melting Time

The thermal heat storage it’s an effective way to suit the energy availability with the demand schedule. It can be stored in the means of sensible or latent heat, the latter applying a material denominated Phase Change Material (PCM), which is provided as organic compounds, hydrated salts, paraffins, among others. The latent heat storage systems offer several advantages, like the practically isothermal process of loading and unloading and the high energy density. However, the low thermal conductivity makes the cycle prolonged on these systems, restricting its applicability. Applying computational fluid dynamics, the behavior of the PCM melting process was studied in cylindrical cavities with horizontal and vertical fins, aiming the optimization of the fin geometry. In this way the fin area was kept constant, varying its aspect ratio. The numerical model was validated with results from the literature and it’s composed of the continuity, momentum and energy equations increased by the phase change model. Qualitative and quantitative results are presented, referring to mesh independence, contours of velocity, net fraction and temperature at different moments of the process. The results of the study indicate that the position of the fin in the heat exchanger influences the melting process, although the vertical fins have a faster total melting process, horizontal fins can reach larger partial liquid fractions in less time in the heat exchanger. Such as the position of the fin, the increase of its length propitiates the reduction of the melting time, evidencing the optimal aspect ratio.

A Thermal Model for Concentric-Tube Overfire Air Ports

2009 ◽  
Vol 1 (1) ◽  
Author(s):  
Larry W. Swanson ◽  
David K. Moyeda
Keyword(s):  
Heat Source ◽  
Wall Temperature ◽  
Tube Wall ◽  
Operating Conditions ◽  
Transfer Model ◽  
Radiation Boundary Condition ◽  
Temperature Distributions ◽  
Airflow Distribution ◽  
Highly Nonlinear ◽  
Tube Wall Temperature

A quasisteady multimode heat-transfer model for boiler concentric-tube overfire air ports has been developed that predicts the effect of geometry, furnace heat source and heat sink temperatures, axial injector wall conduction, and coolant flow rate on the tube wall temperature distributions. The model imposes a radiation boundary condition at the outlet tip of the ports, which acts as a heat source. The model was validated using field data and showed that both the airflow distribution in the ports and tube diameter can be used to control the maximum tube wall temperature. This helps avoid tube overheating and thermal degradation. For nominal operating conditions, highly nonlinear axial temperature distributions were observed in both tubes near the hot outlet end of the port.

Nozzle tube-wall temperature measurement by radiometric techniques.

1966 ◽  
Vol 3 (7) ◽  
pp. 1144-1146
Author(s):  
E. L. GEERY ◽  
W. R. THOMPSON ◽  
J. H. BEVERIDGE ◽  
W. J. HELM
Keyword(s):  
Temperature Measurement ◽  
Wall Temperature ◽  
Tube Wall ◽  
Tube Wall Temperature
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