Heat Exchanger
A heat exchanger is a device that transfers thermal energy between two or more fluids (liquids, gases, or a combination) without mixing them. They are widely used in industries like power generation, HVAC, refrigeration, chemical processing, and automotive systems.
Types of Heat Exchangers
1. Based on Construction & Design
| Type | Description | Applications |
| Shell and Tube | One fluid flows inside tubes, another outside in a shell. High pressure/temperature handling. | Power plants, oil refineries, chemical processing |
| Plate Heat Exchanger | Thin plates with gaskets or welded designs for compact heat transfer. | HVAC, food processing, refrigeration |
| Double Pipe (Hairpin) | Simple concentric pipes (one fluid inside, another outside). | Small-scale industrial processes |
| Finned Tube | Tubes with fins to increase surface area for better air/fluid heat transfer. | Air conditioners, radiators |
| Spiral | Coiled design for handling viscous or fouling fluids. | Waste heat recovery, pulp & paper industry |
2. Based on Flow Arrangement
- Parallel Flow – Both fluids move in the same direction (lower efficiency).
- Counter Flow – Fluids move in opposite directions (most efficient).
- Cross Flow – Fluids move perpendicular to each other (common in radiators).
Working Principle
Heat exchangers operate on the principle of thermal conduction and convection:
- Hot Fluid Inlet – Enters one side of the exchanger.
- Heat Transfer – Energy moves from the hotter to the colder fluid through a solid barrier (tube/plate wall).
- Cold Fluid Outlet – Absorbs heat and exits at a higher temperature.
- Hot Fluid Outlet – Cools down and exits the system.
Key Components
- Tubes/Plates – Primary heat transfer surfaces.
- Shell/Casing – Encloses the fluids.
- Baffles (in shell & tube) – Direct flow for better efficiency.
- Gaskets/Seals (in plate exchangers) – Prevent leaks.
- Fins – Enhance heat transfer in air-cooled exchangers.
Applications
✔ Power Plants – Condensers, feedwater heaters.
✔ HVAC Systems – Chillers, boilers, radiators.
✔ Oil & Gas – Refineries, heat recovery systems.
✔ Automotive – Radiators, intercoolers, oil coolers.
✔ Food & Beverage – Pasteurization, sterilization