"膜片式热交换器" can be translated as "diaphragm-type heat exchanger" or "membrane-type heat exchanger" in English.
"Diaphragm" often refers to a thin, flexible, or semi-rigid partition, which can be applicable depending on the specific design of the heat exchanger.
"Membrane" emphasizes the thin, sheet-like structure used for separation or heat transfer, which is also a fitting description for this type of heat exchanger.
Both terms are commonly used in technical literature, and the choice between them may depend on the specific context or the preferred terminology in the relevant industry.