Using the high-temp flue gas and natural gas as the driving heat resource, the flue gas and direct fired LiBr absorption chiller (The chiller/The unit) utilizes the refirgerant water’s evaporation to produce chilled water.
In our daily life, as we all know that, we will feel cool if dripping some alcohol on the skin, that’s because the evaporation will absorb heat from our skin. Not only alcohol, all other kinds liquid will absorb surrounding heat while evaporation. And the lower the atmospheric pressure, the lower the vaporation temperature. For example, the water boiling temp is 100℃ under 1 atmosphere of pressure, but if the atmospheric pressure drops to 0.00891, the water boiling temp beomes to 5℃.That’s why under vacuum conditions, water can vaporize at very low temp.
That is the basic working principle of a multi energy LiBr absorption chiller. Water(refrigerant) vaporizes in the high-vacuum absorber and absorbs heat from the water which is to be cooled. The refrigerant vapor is then absorbed by the LiBr solution(absorbent) and circulated by pumps. The process repeats.
Cooling cycle
The working principle of the multi energy LiBr absorption chiller is shown as Figure 2-1. The diluted solution from the absorber, pumped by the solution pump, passes the low-temp heat exchanger(LTHE) and high-temp heat exchanger(HTHE), then enters the high-temp generator(HTG), where it is boiled by the high-temp flue gas and naturak gas to generate high-pressure, high-temp refrigerant vapor. The diluted solution turns into intermediate solution.
The intermediate solution flows via HTHE into the low-temp generator(LTG), where it is heated by the refrigerant vapor from HTG to generate refrigerant vapor. The intermediate solution becomes concentrated solution.
The high-pressure, high-temp refrigerant vapor generated by HTG, after heating the intermediate solution in LTG, condenses into refrigerant water. The water, after being throttled, together with the refrigerant vapor generated in LTG, enter the condenser and be cooled by the cooling water and turns into refrigerant water.
The refrigerant water generated in the condenser passes a U-pipe and flows into the evaporator. Part of the refrigerant water vaporizes due to the very low pressure in the evaporator, while the majority of it is driven by the refrigerant pump and sprayed on the evaporator tube bundle. The refrigerant water sprayed on the tube bundle then absorbs the heat from the water flowing in the tube bundle and vaporizes.
The concentrated solution from LTG flows via LTHE into the absorber and is sprayed on the tube bundle. Then, after being cooled by the water flowing in the tube bundle, the concentrated solution absorbs the refrigerant vapor from the evaporator and becomes diluted solution. In this way, the concentrated solution continuously absorbs the refrigerant vapor generated in the evaporator, keeping the evaporation process continuing. In the meantime, the diluted solution is transmitted by the solution pump to HTG, where it is boiled and concentrated again. Thus a cooling cycle is completed by multi energy LiBr absorption chiller and the cycle repeats.