Abstract: The structure, method of fabrication and uses of enclosed double plate heat transfer panels with prefabricated main panel bodies are introduced. In most applications, a pane is used to conduct a gas-liquid interaction such as vaporization, condesation, gas absorption, gas description, endothermic and exothermic chemical reactions inside while having a heat interaction with a fluid outside that undergoes a complementary operation. A panel (41) incorporates one or more of the following key features:(a) It comprises a prefabricated main body (42) and two reinforced mainfold conduits (47) and (49) welded to the main panel body by welds (45).(b) It has nozzles (48) for applying a liquid film inside the panel.(c) The inside surfaces (51) are textured to improve wettability and drainage.