Abstract: An unsaturated polyester resin composition contains an unsaturated polyester, a vinyl ester, a polymerizable monomer, and an aluminum hydroxide. The vinyl ester is a reaction product of an epoxy resin and an unsaturated monobasic acid. The vinyl ester is blended in a predetermined ratio to the unsaturated polyester. The aluminum hydroxide is blended in a predetermined ratio to the vinyl ester.

Abstract: A heat exchanger comprises a plurality of regularly corrugated fins placed one over another in layers at regular pitches in a back-to-back arrangement so as to form alternate wide and narrow fluid passage between the adjacent corrugated fins, and each having a plurality of small through holes, a plurality of collars formed in a staggered arrangement, and an annular area not having any small through hole and formed so as to surround the root of each collar; and pipes for passing a secondary fluid therethrough, each inserted through the collars of the layers of the corrugated fins. The height of the collar from the lower surface of the annular area corresponds to the pitch between the adjacent corrugated fins, and thereby the corrugated fins can be assembled at regular pitches simply by placing one over another. The pipes are expanded after being inserted through the collars so that the pipes are firmly and closely joined to the collars for satisfactory heat transmission between the fins and the pipes.

Abstract: A heat exchanger comprises a plurality of perforated and regularly corrugated heat transfer plates arranged in a ridge-to-ridge and furrow-to-furrow arrangement, so as to form primary fluid passages each consisting of alternate expanded sections and narrowed sections arranged along the direction of flow of a primary fluid, and a plurality of pipes for passing a secondary fluid therethrough, the pipes penetrating through and across the heat transfer plates. Oblique guide grooves are formed in the surfaces of each heat transfer plates to facilitate the downward flow of the condensate condensed over the surfaces of the heat transfer plates, the grooves being inclined closer to the vertical than to the horizontal to facilitate downward flow of any vapor condensed on the plates from the primary fluid whereby the heat transfer plates dry quickly for efficient heat exchange between the primary and secondary fluids.