tailieunhanh - Mechanical Science HandbooksMechanical Science Handbooks 10000 Part 9

Tham khảo tài liệu 'mechanical science handbooksmechanical science handbooks 10000 part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Heat Exchangers DOE-HDBK-1018 1-93 HEAT EXCHANGER APPLICATIONS This means the feedwater is exposed to the condensed steam first and then travels through the tubes and back around to the top right end of the heat exchanger. After making the 180 bend the partially heated feedwater is then subjected to the hotter steam entering the shell side. The feedwater is further heated by the hot steam and then exits the heat exchanger. In this type of heat exchanger the shell side fluid level is very important in determining the efficiency of the heat exchanger as the shell side fluid level determines the number of tubes exposed to the hot steam. Radiator Commonly heat exchangers are thought of as liquid-to-liquid devices only. But a heat exchanger is any device that transfers heat from one fluid to another. Some of a facility s equipment depend on air-to-liquid heat exchangers. The most familiar example of an air-to-liquid heat exchanger is a car radiator. The coolant flowing in the engine picks up heat from the engine block and carries it to the radiator. From the radiator the hot coolant flows into the tube side of the radiator heat exchanger . The relatively cool air flowing over the outside of the tubes picks up the heat reducing the temperature of the coolant. Rev. 0 Page 13 ME-02 HEAT EXCHANGER APPLICATIONS DOE-HDBK-1018 1-93 Heat Exchangers Because air is such a poor conductor of heat the heat transfer area between the metal of the radiator and the air must be maximized. This is done by using fins on the outside of the tubes. The fins improve the efficiency of a heat exchanger and are commonly found on most liquid-to-air heat exchangers and in some high efficiency liquid-to-liquid heat exchangers. Air Conditioner Evaporator and Condenser All air conditioning systems contain at least two heat exchangers usually called the evaporator and the condenser. In either case evaporator or condenser the refrigerant flows into the heat exchanger and transfers heat either gaining or