scholarly journals The additional heat flux due to adhesion at a partially immersed rotating drum heat exchanger for latent heat storage

2021 ◽  
Vol 2116 (1) ◽  
pp. 012097
Author(s):  
J Tombrink ◽  
E Jung ◽  
D Bauer
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Exchanger ◽  
Liquid Phase ◽  
Phase Change ◽  
Layer Thickness ◽  
Phase Change Material ◽  
Rotating Drum ◽  
Additional Heat ◽  
Change Material

Abstract Latent heat storages can be used to store thermal energy at a constant temperature. By actively removing the solidified phase change material from the heat exchanger surface during the discharge process, the heat flux can be kept constant and a separation of power and capacity is possible. In the presented rotating drum concept, a cooled drum is partially immersed in a tub of liquid phase change material and rotates in it. Phase change material solidifies at the submerged part of the drum. In addition, adhering liquid phase change material solidifies after the surface has left the tub. In this paper, the additional heat transfer due to adhesion is examined by determining the solidified layer thickness as well as the heat transfer by comparing measurements with adhesion and while eliminating the adhesion with a rubber lip. The measured adhering layer thickness differs by 33% from a presented analytical approach. The transferred heat is increased up to 26 % due to the adhesion.

Second-Law Efficiency of an Energy Storage-Removal Cycle in a Phase-Change Material Shell-and-Tube Heat Exchanger

1993 ◽  
Vol 115 (4) ◽  
pp. 240-243 ◽  
Author(s):  
Ch. Charach
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Heat Storage ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Change Material

This communication extends the thermodynamic analysis of latent heat storage in a shell-and-tube heat exchanger, developed recently, to the complete heat storage-removal cycle. Conditions for the cyclic operation of this system are formulated within the quasi-steady approximation for the axisymmetric two-dimensional conduction-controlled phase change. Explicit expressions for the overall number of entropy generation units that account for heat transfer and pressure drop irreversibilities are derived. Optimization of this figure of merit with respect to the freezing point of the phase-change material and with respect to the number of heat transfer units is analyzed. When the frictional irreversibilities of the heat removal stage are negligible, the results of these studies are in agreement with those developed recently by De Lucia and Bejan (1991) for a one-dimensional latent heat storage system.

Forced Flow and Convective Heat Transfer of Phase Change Material Slurry in the Heat Exchangers

2010 ◽  
Author(s):  
Peng Zhang ◽  
Zhiwei Ma ◽  
Ruzhu Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Flow Rate ◽  
Tetrabutylammonium Bromide ◽  
Forced Flow ◽  
Experimental Investigations ◽  
Cooling Power ◽  
Change Material

The application of phase change material slurry to the refrigeration and air conditioning system opens a new way for energy saving and reduction of the quantity of refrigerant in the system, because it can serve as both the energy storage and transportation media in the secondary loop which is responsible for distributing the cooling power. In the present study, the experimental investigations of the forced flow and heat transfer characteristics of Tetrabutylammonium Bromide (TBAB in abbreviation) clathrate hydrate slurry (CHS) in both the plate heat exchanger (PHE) and double-tube heat exchanger (DHE) are carried out. It is found out that the pressure drop in the PHE is about 5–50 kPa at the flow rate of 2–14 L/min and is about 2–30 kPa at the flow rate of 3–14 L/min, which is nearly 2 times of that of the chilled water. The overall heat transfer coefficient is in the range of 2500–5000 W/(m2K) for TBAB CHS in the PHE and is about 1500–3500 W/(m2K) in the DHE, which are both higher than that of TBAB aqueous solution flow because of the involvement of the phase change of TBAB CHS.

scholarly journals Application of Phase Change Material-Based Thermal Capacitor in Double Tube Heat Exchanger—A Numerical Investigation

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4327
Author(s):  
Matthew Fong ◽  
Jundika Kurnia ◽  
Agus P. Sasmito
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Oscillation Period ◽  
Temperature Oscillation ◽  
Tube Heat Exchanger ◽  
Inlet Conditions ◽  
Change Material

In many heat transfer related applications, there is a need for a stable, constant supply temperature. As a result, the integration of intermittent renewable sources of heat into these processes can prove to be challenging, requiring special temperature smoothing devices or strategies. This study focuses on the application of phase change materials integrated into a double tube heat exchanger as a possible thermal smoothing device. The objective of this study is to evaluate the ability of the exchanger to smoothen out temperature variations within the cold stream outlet while the hot stream is subject to oscillating inlet conditions. A computational fluid dynamics approach is used where a numerical model is developed, validated and then used to model the conjugate heat transfer within the heat exchanger. Four organic phase change materials (PCM) with different phase change temperatures were selected for investigation (myristic, octadecane, eicosane, and wax) to study the relationship between melting temperature and stabilization performance. A parametric study was then conducted by varying the Reynolds number of the flow as well as temperature oscillation period and amplitude to study the sensitivity of the system. The results confirm the potential of a phase change material-based thermal capacitor at dampening oscillations across the heat exchanger.

Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid in Microchannels

2009 ◽  
Author(s):  
Satyanarayana Kondle ◽  
Jorge L. Alvarado ◽  
Charles Marsh ◽  
Dave Kessler ◽  
Peter Stynoski
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Laminar Flow ◽  
Boundary Conditions ◽  
Phase Change ◽  
Phase Change Material ◽  
Aspect Ratios ◽  
Transfer Behavior ◽  
Peripheral Temperature ◽  
Change Material

In this paper, a PCM fluid is compared with pure water as heat transfer fluid. The heat transfer behavior of phase change material fluid (PCM) under laminar flow conditions in circular and rectangular microchannels was studied numerically. As part of the numerical study, an effective specific heat technique was used to model the phase change process. Heat transfer results for smooth circular and rectangular microchannels with PCM fluid were obtained under hydrodynamically and thermally fully developed conditions. A PCM fluid in microchannels with different aspect ratios was found to exhibit unique thermal behavior which could be beneficial in electronic cooling applications. As a part of boundary conditions, the flow was assumed to be hydrodynamically fully developed at the inlet and thermally developing inside the microchannel. Heat transfer characteristics of PCM slurry flow in microchannels of various aspect ratios have been studied under three types of wall boundary conditions including constant axial heat flux with constant peripheral temperature (H1), constant heat flux with variable peripheral temperature (H2), and constant wall temperature (T) boundary condition. Effects of phase change on the heat transfer were determined using a specific heat model, which includes the effect of latent heat of fusion of the phase change material. The fully developed Nusselt number was found to be higher for H1 than for H2 and T boundary conditions for all the geometries.

scholarly journals Phase Change Material Melting Process in a Thermal Energy Storage System for Applications in Buildings

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3254 ◽  
Author(s):  
Túlio Nascimento Porto ◽  
João M. P. Q. Delgado ◽  
Ana Sofia Guimarães ◽  
Hortência Luma Fernandes Magalhães ◽  
Gicelia Moreira ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Storage ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Melting Process ◽  
Average Heat ◽  
Change Material

The development of thermal energy storage systems is a possible solution in the search for reductions in the difference between the global energy supply and demand. In this context, the ability of some materials, the so-called phase change materials (PCMs), to absorb and release large amounts of energy under specific periods and operating conditions has been verified. The applications of these materials are limited due to their low thermal conductivity, and thus, it is necessary to associate them with high-conductivity materials, such as metals, to make the control of energy absorption and release times possible. Bearing this in mind, this paper presents a numerical analysis of the melting process of a PCM into a triplex tube heat exchanger (TTHX) with finned copper tubes, which allowed for the heat transfer between a heating fluid (water) and the phase change material to power a liquid-desiccant air conditioning system. Through the analysis of the temperature fields, liquid fractions, and velocities, as well as the phase transition, it was possible to describe the material charging process; then, the results were compared with experimental data, which are available in the specialized literature, and presented mean errors of less than 10%. The total required time to completely melt the PCM was about 105.5 min with the water being injected into the TTHX at a flow rate of 8.3 L/min and a temperature of 90 °C. It was observed that the latent energy that accumulated during the melting process was 1330 kJ, while the accumulated sensitive energy was 835 kJ. The average heat flux at the internal surface of the inner tube was about 3 times higher than the average heat flux at the outer surface of the TTHX intermediate tube due to the velocity gradients that developed in the internal part of the heat exchanger, and was about 10 times more intense than those observed in the external region of the equipment.

Sign in / Sign up

Export Citation Format

Share Document