Abstract: Method and apparatus are disclosed for an engine cooling system with the coolant fluid maintained in a state of nucleate boiling at a selected location in the coolant passages of the engine. The cooling system comprises a radiator and a coolant reservoir with a variable speed circulating pump for circulating the coolant through the coolant passages in the engine and through the radiator. A coolant pressure pump with a servo motor is adapted to pump coolant between the radiator and the reservoir as needed and to adjust the static pressure of the coolant. The coolant flow through the radiator is adjusted to maintain the coolant at a selected location at a control temperature which will maintain a safe metal operating temperature for the engine. The static pressure of the coolant is adjusted to a value at which the saturation temperature of the coolant is near the control temperature so that nucleate boiling will occur at the selected location.

Abstract: The reinforcements in a radiator core assembly are perforated so as to form a shear zone in the legs thereof that maintain rigidity in the reinforcements for stacking and brazing and can be readily sheared thereafter.

Abstract: A motor vehicle tube and fin heat exchanger is disclosed comprising a plurality of tubes arranged in spaced side-by-side relationship and a plurality of louvered fins arranged in spaced side-by-side relationship and between and in heat transfer relationship with adjacent ones of the tubes. The fins preferably have a thickness and stacked density such as to constitute not more than 12% nor less than 2.5% of the space between the adjacent tubes, a total louvered area not more than 60% nor less the 40% of the total fin area, and a linear fin edge projection density of not more than 1.2 mm.sup.-1 nor less than 0.68 mm.sup.-1.

Abstract: A tube and fin heat exchanger is disclosed comprising a pair of tanks, a plurality of tubes of non-circular cross section connected at their ends to tanks, and a plurality of corrugated fin strips each arranged between and extending along the length of adjacent ones of the tubes. Each of the fin strips has a constant corrugation spacing extending along an intermediate and almost the entire length of the tubes and a smaller corrugation spacing extending the remainder of the length of the tubes to their ends so as to provide increased resistance to ballooning of the tubes at their ends by internal pressure.

Abstract: A detachable insert for solar absorbers with flow-through headers is disclosed which adapts such headers to vertical as well as horizontal mounting without fluid stagnation and with full drainability. The insert is insertable in the lowermost unused header leg of one of the headers when the headers are vertically oriented and sealingly plugs off the length thereof below the lowermost one of the longitudinal passages which interconnect the headers.