Internal energy and exergy recovery in high temperature application absorption heat transformers

• Triple absorption heat transformer internal heat recovery dissected and optimised.
• Optimised designs created using heat exchange network modelling.
• One heat exchanger in conventional unit proven almost irrelevant at high GTLs.
• Rearranging heat exchangers increases COP by 11.7% and reduces exergy losses by 21%.
• One extra heat exchanger increases COP by 16.4% and reduces exergy losses by 28%.

In this paper, the design of a triple absorption heat transformer (TAHT) using the working fluids water and lithium bromide is dissected and reassembled using heat exchange network modelling in order to determine the optimum number and locations of internal heat exchange units within the system. It is found that the conventional design of the TAHT does not employ heat exchangers effectively, and that thus by rearranging these units system COP may be increased by 11.7% while exergy destruction within the system (its irreversibility) can be reduced by 21%. Strategically adding an extra one or two heat exchangers increases the COP by 16.4% and 18.8% while decreasing exergy destruction by 28% and 31.5% respectively compared to a conventional TAHT design.