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A review of the experimental and theoretical investigations of the heat transfer characteristics of composite cylinders is presented. While there are more studies devoted to thermal conduction through cylindrical contacts than there were six years ago, this phenomenon is rather underrepresented in the literature. Some studies are more theoretical in nature, dealing primarily with fundamental issues, and are broadly classi ed as general studies; others are experimentally based and are classi ed as applications studies. Tabulations of previously published correlations, and gures demonstrating the range of available data in these categories are also presented. Much of the available data for the general studies are presented in the form of a dimensionless thermal contact conductance as a function of dimensionless interface heat ux. A correlation for the prediction of the dimensionless contact conductance of composite cylinders has been proposed. Based on this review, it is evident that some areas of cylindrical thermal contact conductance have not been adequately investigated. There are still many gaps in our understanding of cylindrical contacts that need to be explored. Nomenclaturespeci c heat at constant volume c = outer radius d = Vickers indention diameter, m d o = tube outer diameter E = elastic modulus F( ) = eigenfunction f( ) = interface heat ux distribution fpi = number of ns per unit length H = bulk microhardness H e = effective microhardness H m = Meyer hardness h* = dimensionless conductance h c = contact conductance I = tube expansion, interference k = conductivity k e= effective (geometric mean) conductivity k g0 = gap gas thermal conductivity k n = eigenvalue k s = harmonic mean of thermal conductivity of joint materials L = n collar length = contact length m = effective asperity slope (geometric mean) m i = asperity slope of surface i N uc = joint conductance P = ambient pressure P atm = atmospheric pressure P c = contact pressure Pr = Prandtl number Q = thermal load q = interface heat ux q* = dimensionless heat ux R* = overall thermal resistance without gap resistance R c = contact resistance, 1/hc R g = gap resistance R i = inside thermal resistance, including lm and fouling R o = outside thermal resistance including lm and fouling r i = inner radius of shell i T = temperature T a = temperature at radius a, ambient bulk uid temperature T b = temperature at radius b, n base temperature T c = temperature at radius c T 0 = fabrication temperature for n and tube t = n thickness u c = initial interference at interface Y = mean plane separation = accommodation parameter f = linear thermal expansion coef cient of n material t = linear thermal expansion coef cient of tube material = uid parameter, coef cient of thermal expansion T m = mean temperature difference across interface i = casing thickness for shell i = molecular mean free path i = thermal conductivity of inner tube o = thermal conductivity of outer tube = parameter = Poisson ratio = parameter i = surface roughness of material i a = contact spot...