K. Ramamurthi

Bio: K. Ramamurthi is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Liquid nitrogen & Conductance. The author has an hindex of 2, co-authored 2 publications receiving 7 citations.

Thermal contact conductance of molybdenum-sulphide-coated joints at low temperature

Abstract: J OINTS used for cryogenic structural supports and satellite deployment mechanisms are often exposed to very low temperatures. These joints, unlike those for ground applications, do not usemetal-to-metal contact. A conducting or insulating interstitial medium is introduced at the interface for controlling the contact conductance. When gold and silver plating and the use of thermal grease is adopted for enhancing the contact conductance, a reduction in contact conductance is achieved by providing a nonmetallic coating at the interfaces. Molybdenum sulphide (MoS2) is widely used as the nonmetallic coating in cryogenic structural joints, because it not only reduces the joint conductance but also provides dry lubrication at the joint. A precise knowledge of the contact conductance of the coated joint is essential, especially at the low temperatures at which it is used for estimating the parasitic heat-conduction loads through the cryogenic structural supports. A variety of nonmetallic coatings such as manganese dioxide, silicon elastomer, carbon black, and polyethylene have been evaluated over a range of interface temperatures and pressures [1,2]. The temperatures considered in the preceding studies are essentially above the ambient. A general model for computing the conductance in multilayered contacts was developed by Muzychka et al. [3] for a flux tube having two applied coatings. The need remains to determine contact conductance of nonmetallic coating [4] such as MoS2 at low temperatures. In this paper, the effectiveness of MoS2 coating on aluminumand stainless steel contacts at different interface temperatures and loads is determined. Experiments are carried out over a range of low temperatures.

Literature Survey of Numerical Heat Transfer (2000–2009): Part II

Abstract: A comprehensive survey of the literature in the area of numerical heat transfer (NHT) published between 2000 and 2009 has been conducted Due to the immenseness of the literature volume, the survey

Review of prediction for thermal contact resistance

Abstract: Theoretical prediction research on thermal contact resistance is reviewed in this paper. In general, modeling or simulating the thermal contact resistance involves several aspects, including the descriptions of surface topography, the analysis of micro mechanical deformation, and the thermal models. Some key problems are proposed for accurately predicting the thermal resistance of two solid contact surfaces. We provide a perspective on further promising research, which would be beneficial to understanding mechanisms and engineering applications of the thermal contact resistance in heat transport phenomena.

Thermal Design Procedure for Micro- and Nanosatellites Pointing to Earth

Abstract: This paper proposes a thermal design procedure for micro- and nanosatellites that can be completed in one year. Two thermal design concepts keep components within their design temperature range, reducing the temperature change by using the whole structure for heat storage and reducing the temperature change of the inner structure where the most temperature-sensitive components are mounted. One- and two-nodal analysis methods are used for the former and latter concepts, respectively, to clarify the combinations of optical properties for the structures and components to keep within the design temperature range of the components. Finally, multinodal analysis is performed for detail design based on the optical properties clarified from the one- and two-nodal analyses. This thermal design procedure was applied to the Hodoyoshi-1 satellite, which is a cube about 50 cm on a side, has two inner plates and has solar cells on the body, is on a sun-synchronous orbit at an altitude of about 500 km, and is pointing to...