Phase Change Material Suspensions Research Articles

Laminar forced convection heat transfer with phase change material emulsions

Results of an experimental study of laminar forced convection heat transfer in a circular duct with a phase change material emulsion (n-octadecane in water) are presented in this paper. The bulk Stefan numbers considered in this study range up to 3.0 and the concentration of phase change material range up to 30% by volume. The results show that the heat transfer characteristics for phase change material emulsions are similar to those of microencapsulated phase change material suspensions, thus confirming that the microcapsule walls do not affect the heat transfer process significantly.

Natural Convection Heat Transfer from A Vertical Flat Plate with Phase Change Material Suspensions

Natural Convection Heat Transfer from A Vertical Flat Plate with Phase Change Material Suspensions

Microencapsulated phase-change material suspensions for heat transfer in spacecraft thermal systems

The potential for improvement of liquid-coupled heat exchange by utilizing a two-component suspension consisting of a carrier fluid and a microencapsulated phase-change material is presented. A system analysis utilizing a water suspension shows the effects on system behavior. Enhancement of fluid heat capacity and heat transfer coefficient is shown, along with reductions of system temperatures. Results of experiments are presented in which 10-30-/L*m particles of various microencapsulated paraffins were slurried with water as well as silicone oil and circulated in a model heat exchange loop. Enhancement of heat transfer coefficients and thermal properties, and reductions in system temperatures, are shown to occur experimentally. Significant improvements in overall performance are shown to be achievable. *

Analysis of forced convection heat transfer in microencapsulated phase change material suspensions

B = Bi, = C = C* = C = E= = e = Fo = h, = K, = k = L = rn = Nu, = Pe = 4 = R = Rd = Re = r = r* = r,. = r,, = Is1. = Ste = S = T= t = u = 47, = X = X = a = A numerical solution of laminar forced convection heat transfer of a microencapsulated phase change material suspension in a circular tuhe with constant heat flux has been presented in this article. Melting in the microcapsule was solved by a temperature transforming model instead of a quasisteady model. The effects of the microcapsules crust, the initial subcooling, and the width of the phase change temperature range on the variation of the dimensionless tuhe wall temperatures, along the axial direction, were also considered in the present model. The agreement between the present numerical results and the experimental results is very good.

Laminar forced convection heat transfer in microcapsulated phase change material suspensions

An experimental study using a suspension of n- eicosane microcapsules in water was conducted in order to evaluate the heat transfer characteristics of phase change material suspensions. Experiments were done for laminar, hydrodynamically fully developed flows in a circular duct with a constant wall heat flux. The temperature of the suspension entering the test section was maintained at or below the melting point of the phase change material. The primary parameters in the study were the bulk Stefan number and the volumetric concentration. In addition, a few experiments were conducted to evaluate the effect of particle diameter and degree of homogeneity of the suspension. The heat fluxes chosen for the experiments were typical of low temperature applications (below 60°C). Results show that use of phase change material suspensions can reduce the rise in wall temperature by up to 50% as compared to a single phase fluid for the same non-dimensional parameters. The most dominant parameter influencing the heat transfer was found to be the bulk Stefan number. The effect of concentration was found to be insignificant by itself, though its influence is felt indirectly through the bulk Stefan number. An increase in particle diameter by a factor of 2.5 was found to further reduce the wall temperature rise by 15%. The degree of homogeneity of the suspension had no observable effect on the wall temperatures.

The performance of liquid heat sinks with phase change material suspensions

Results of an experimental study to investigate the performance of liquid heat sinks with microencapsulated phase change material suspensions are presented. The volumetric concentrations of microcapsules in the suspension was varied from 0% to 28%. For the case of heating from below, the use of phase change material suspensions was found to be detrimental to the overall heat transfer because of a reduced convection due to the presence of microcapsules. In contrast, the performance of the liquid heat sink is improved when heating is from above.