| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a compact heat exchanger having high heat exchanging efficiency which can be utilized for preheating fuel being supplied to an internal combustion engine. SOLUTION: A tubular heater unit 2 is disposed concentrically in a tubular casing 1 and a heat exchanging coil 3 for passing fluid being heated comprises an inner tubular coil part 18 contiguous to the inner side of the tubular heater unit 2, and an outer tubular coil part 20 contiguous to the outer side of the tubular heater unit 2 and interconnected with one end of the inner tubular coil part 18 wherein the annular space between the tubular casing 1 and the outer tubular coil part 20 is filled with a thermal insulation material 4.</p> |
