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Abstract
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Improving the performance of heat transformer systems is critical for achieving sustainable seawater desalination. This study proposes two new modified configurations of a double absorption heat transformer for enhancing
the quality of moderate waste heat to generate sustainable distilled water. At first, the performances of cycles are
investigated and compared based on the first and second principles of thermodynamics using the Engineering
Equation Solver software. Results show that the two proposed schemes have higher performance compared to the
base scheme in all studied ranges. The second scheme, however, has the highest total pure water vapor production rate. So, it is selected for optimization. Single and multi-objective optimizations are carried out, and the
results show that third multi-objective optimal design (MOOD 3) has the best coefficient of performance and pure
water vapor production rates, reasonable for regions and applications in need of high pure water vapor and
thermodynamic enhancement, valued at 0.3286 and 0.2259 kg/s, respectively. More detailed investigation is
carried out by performing advanced exergy analysis on the second optimized scheme and MOOD 3 condition.
First and second splitting levels of exergy destruction as well as analyzing of detailed exogenous exergy
destruction parts, are determined for each system component and the total system. The results show that 41 %
(63.6 kW) of the total irreversibility rate of the modified cycle is avoidable; thus, the cycle has substantial potential for improvement. Also, the advanced exergy analysis proposes this component order for improvement: the
generator assembly, the evaporator, the condenser, the absorber, the absorber/evaporator assembly, economizer
3, economizer 1, and economizer 2. This order is different from the one attained by the conventional exergy
analysis.
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