Abstract: A plate-fin-type heat exchanger for transferring heat from a hot fluid to a cold fluid includes stacked plates having fins therebetween that define alternate interdigitated first and second fluid passages, the fins defining the first fluid passages having a high coefficient of heat transfer and a large area of heat transfer and the fins defining the second fluid passages having a low coefficient of heat transfer and a small area of heat transfer. Either the hot fluid or the cold fluid is continuously passed through the first fluid passages and the other fluid is intermittently passed through the second fluid passages.

Abstract: A grout injection method and apparatus, characterized in that a grout comprised of two liquids and curable when the two liquids are combined are supplied, in a grout injection operation, to an injection pump, introduced through separate passages formed concentrically in the pipe, respectively, into an annular chamber formed within the pipe, and uniformly combined, contacted and mixed with each other in the annular mixing chamber before injection into the soil. The passages of the liquids communicating with the annular mixing chamber are blocked when the grout injection is not carried out.