What type of heat exchanger involves phase change in the cooling or heating fluid?

What type of heat exchanger involves phase change in the cooling or heating fluid?

• A. Two Phase
• B. Direct Contact
• C. Indirect Contact
• D. Plate and Frame

Answer: (A)

When heat is transferred with a phase change in the fluid, you’re dealing with a two-phase heat transfer process. In these exchangers, the working fluid actually changes between liquid and vapor (boiling or condensing) while transferring heat, so both phases are present and latent heat drives the transfer. This makes two-phase exchangers particularly efficient for large heat duties and nearly constant temperatures during the phase-change region, as in condensers and evaporators. Other configurations focus on how the fluids are arranged or separated rather than on phase change. Indirect-contact and plate-and-frame exchangers transfer heat through a wall and typically operate with single-phase fluids, while direct-contact exchangers involve mixing fluids and are defined by contact rather than the need for phase change. Hence, the type that explicitly involves phase change in the cooling or heating fluid is the two-phase heat exchanger.

When heat is transferred with a phase change in the fluid, you’re dealing with a two-phase heat transfer process. In these exchangers, the working fluid actually changes between liquid and vapor (boiling or condensing) while transferring heat, so both phases are present and latent heat drives the transfer. This makes two-phase exchangers particularly efficient for large heat duties and nearly constant temperatures during the phase-change region, as in condensers and evaporators.

Other configurations focus on how the fluids are arranged or separated rather than on phase change. Indirect-contact and plate-and-frame exchangers transfer heat through a wall and typically operate with single-phase fluids, while direct-contact exchangers involve mixing fluids and are defined by contact rather than the need for phase change. Hence, the type that explicitly involves phase change in the cooling or heating fluid is the two-phase heat exchanger.