Experimental study of the transient heat transfer across periodically contacting surfaces

Abstract

This study experimentally examines the heat transfer across surfaces which contact and separate at regular intervals. The results are presented for the case of low contact pressure, moderate interface temperature, equal contact and separation times during a cycle, and identical materials on either side of the contact interface. The results are presented in two basic areas: 1) the behavior of the thermal contact resistance during the quasi-steady state; and 2) the length of time required for the temperature distribution in the material to approach the temperature distribution observed in the quasi-steady-state condition. The results indicate that the thermal contact resistance should not be considered a constant for contacts of short duration; and that relatively few cycles are required for the temperature distribution in the material to approach that observed in the quasi-steady state. Nomenclature A-cross-sectional area, m 2 Bi = contact conductance parameter = h c .L/k, dimensionless Fo = Fourier number a t/L 2 , dimensionless h c = thermal contact conductance = l/R c , W/m 2 C h c ss = steady-state thermal contact resistance, W/m 2 C h () = convective coefficient at x = 0, W/m 2 C h -, / = convective coefficient at x = 2L, W/m 2 C k = thermal conductivity, W/mC L = specimen length, m L* = dimensionless length = x/L n = number of cycles required to reach the quasi-steady state, dimensionless Q = heat transfer at the contact interface, W R c = thermal contact resistance, m 2 C/W T(x,t) = generalized temperature distribution, C T c = heat sink fluid temperature, C T /f = heat source fluid temperature, C r* = dimensionless temperature = [T( x 9 t) -T(2L,t)]/[T(Q,t) -T(2L,t)] t-time variable, s t c = contact time, s x = spatial variable, m a = thermal diffusivity, m/s 2

Inverse heat transfer problem of thermal contact conductance estimation in periodically contacting surfaces

“…These results, which are reported by Moses, indicated that, within the accuracy of the recording device, the heat flow down the rod was one-dimensional [13][14]. Table 1 lists the characteristics of the experiment and specimens.…”

“…We consider the actual data taken from a contact conductance experiment conducted by Moses [13][14]. The experimental apparatus, consists of two test cylinders-each held at one end in a thermal reservoir, the supporting frame, and the associated equipment required to bring the test specimens uniformly into and out of contact.…”

“…Moses and Johnson [13] experimentally examined the problem of periodically contacting similar metal surfaces and obtained results that are comparable in both form and magnitude to those of Vick and Ozisik. Moses and Johnson [14] also experimentally examined the approach to the quasi-steady-state condition for similar metallic surfaces in periodic contact, focusing on the behaviour of the TCC during the contact portion of a cycle and on the number of cycles required to reach a quasi-steady state condition. Dodd and Moses [15] extended this set of experiments to consider periodic contacts between aluminium and stainless steel.…”

Thermal Contact Analysis Using Identification Method

“…Later, Flach and Ozisik [17] employed the inverse heat conduction method for predicting time-dependent thermal contact conductance from temperature measurements taken within the mediums. Moses and Johnson [18] studied identical materials for the case of low constant pressure. The interface temperature was kept moderate for a short time, and the same contact and separation duration in a cycle were used.…”

A Study of Thermal Contact using Nonlinear System Identification Models

“…Moses and Johnson [6] experimentally examined the problem of periodically contacting similar metal surfaces and obtained results that are comparable in both form and magnitude to those of Vick and Ozisik. Moses and Johnson [7] also experimentally examined the approach to the quasisteady-state condition for similar metallic surfaces in periodic contact, focusing on the behavior of the thermal contact conductance during the contact portion of a cycle and on the number of cycles required to reach a quasi-steady state condition. The experimentally obtained temperature distributions from Moses and Johnson also are examined by Beck as an example of a parameter and function estimation technique for the inverse heat conduction problem.…”