Heat Exchangers Jordan University of Science （热交换器约旦大学的科学）.pdfVIP

Heat Exchangers Heat exchangers are used to transfer heat between two sources. The exchange can take place between a process stream and a utility stream (cold water, pressurized steam, etc), a process stream and a power source (electric heat), or between two process streams resulting in energy integration and reduction of external heat sources. Typically, a heat exchanger is used with two process streams. However, mutlistream heat exchangers are sometimes used with energy extensive processes, such as LNG processing, to reduce capital cost. The term heat exchanger applies to all equipment used to transfer heat between two streams. However, the term is commonly used to equipment in which two process streams exchange heat with each other. In the other hand, the term heater or cooler is used when the exchange occurs between a process stream and a plant service stream. Other terms used to describe heating equipment include: vaporizer and reboiler (for vaporization) and evaporator (for stream concentration). Exchangers can also be classified as fired (heat source is fuel combustion) and unfired exchangers. There are many types of heat exchangers applied in the process industry. These types include: 1. Hairpin/Double pipe exchangers 2. Shell and tube exchangers 3. Plate and frame exchangers 4. Plate-fin exchangers 5. Spiral heat exchangers 6. Air coolers and condensers 7. Direct contact (quenching towers) 8. Fired heaters The selection of a heat exchanger depends on many factors including capital and operating costs, fouling, corrosion tendency, pressure drop, temperature ranges, and safety issues (tolerance to leakage). Different types of heat exchangers are shown in Figure 42. In process calculations, the main objectives of heat ex