Tham khảo tài liệu 'refrigeration and air conditioning equipment cooling episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 26 OmHht Carrier CocforaUM I Figure 28. Absorption refrigeration cycle. circulated in a closed cycle to the cooling coils. This refrigeration effect is known as flash cooling. 5. In reference to item 3 of figure 28 note the addition of the generator and accessory equipment. These components are necessary for continuous and efficient operation. The salt solution would become diluted and the action stopped if it were not for the regeneration of the salt solution. To keep the salt solution in the absorber at its proper strength so that it will have the ability to absorb water the salt solution is pumped to a generator where heat is used to raise its temperature and boil off the excess water. The salt concentrate is then returned to the absorber to continue its cycle. The water that is boiled off from the salt solution in the generator is condensed in the condenser and returned to the evaporator as shown in item 4 of figure 28. The heat exchanger uses a hot solution from the generator to preheat the diluted solution. This raises the overall efficiency because less heat will be required to bring the diluted solution to a boil. Condensing water which is circulated through the coils of the absorber and the condenser removes waste heat from the unit. By comparing figure 29 with figure 27 you will get a better understanding of the relation between basic operating principles and an actual installation. 6. Controls. Figure 30 illustrates a typical control panel for an absorption refrigeration unit. The purpose of each control listed in this figure is described in the following paragraphs. Turning the off-run-start switch 1 the START position energizes the electric pneumatic switch 2 which activates the control system of the absorption machine. Supply air pressure of 15 . 3 passes to the chilled water thermostat 4 then to the concentration limit thermostat 5 and finally to the capacity control valve 7 . 7. The chilled water thermostat 4 is a direct acting control with a
