The tube and weld materials of a heat pipe heat exchanger must be determined according to the corrosivity of the medium. For media containing chloride ions, 316L stainless steel is recommended; for acidic environments, titanium may be considered; for neutral water systems, carbon steel is sufficient. If inappropriate materials are selected for corrosive media, tube wall thinning or weld leakage may occur, shortening the service life of the equipment.
The working temperature of the heat pipe working fluid must be below the critical temperature and above the freezing point; otherwise, heat transfer capability will decrease or the heat pipe will fail to start. During selection, the medium temperature and its fluctuation range must be provided, based on which working fluids such as water, ammonia, or methanol are selected, and whether the tube wall temperature falls within the applicable range of the working fluid must be verified. For operating conditions with large temperature fluctuations, a safety margin should be reserved.
The allowable pressure drop and installation space determine the fin spacing and structural arrangement. When space is limited, a compact plate-type structure may be used, but the cleanliness of the medium must be evaluated; for fluids containing particles or prone to scaling, shell-and-tube or wide-channel structures should be selected to avoid channel blockage. When pressure drop requirements are strict, the flow cross-sectional area must be increased or the fin density adjusted.
