Investigation of crystallization risk in different types of absorption LiBr/H2O heat transformers

Absorption heat transformers are utilized to upgrade the energy of low-temperature heat sources. When the working fluid in such systems is LiBr/H2O solution, there is a possibility of crystallization phenomenon at their generator outlet. This phenomenon has to be avoided because otherwise it stops the system operation. In the present work, the possibility of crystallization, under different operating conditions such as different temperatures in the condenser, evaporator, absorber and absorbing evaporator temperatures as well as different effectiveness of applied heat exchangers, is investigated. Using engineering equation solver software, the investigation is carried out for three types of heat transformers including single-stage, double-effect and triple-effect for identical values of input heat. The results show that at higher absorber temperatures especially in the double and triple-effect absorption heat transformers, crystallization may occur at the outlet of expansion valves in addition to the generator outlet. Moreover, lower values of the condenser temperature and heat exchangers effectiveness increase the possibility of crystallization risk in all the three types investigated.