A novel hybrid system coupled liquid dehumidification
with absorption
refrigeration driven by solar energy is proposed. Traditional and
advanced exergy and exergoeconomic analyses of the system are conducted
to ascertain the degree of irreversibility and potential improvement
for each component. Based on the advanced exergy and exergoeconomic
analyses, the effects of air humidity, segment temperature, and refrigeration
temperature on the total exergy destruction and cost rates of the
system are obtained. The total avoidable exergy destruction rate,
avoidable exergy destruction cost rate, and avoidable investment cost
rate of the system are selected as objective functions and optimized
by using nondominated sort genetic algorithm-II. The results show
that the total exergy destruction rate and the total exergy destruction
cost rate reach 262.39 kW and 8.563 $/h, respectively. The generator
and regenerator have higher cost rates of the irreversibility overall
system, achieving the values 3.536 and 2.430 $/h, respectively. The
absorber has the highest investment cost rate in the whole system.
The endogenous parts of the exergy destruction and cost rates are
much higher than the exogenous parts in the system. Multiobjective
optimization results show that optimal values for the total avoidable
exergy destruction rate and the exergy destruction cost rate are 50.99
kW and 1.60 $/h, which are 4.15 and 9.14% lower than those calculated
by single-objective optimization, respectively. This study provides
a potential way to utilize solar energy for dehumidification and refrigeration.
To alleviate the energy crisis and reduce CO 2 emissions, a waste heat-driven system coupled with power and refrigeration is proposed. The exergy analysis and advanced exergy analysis are used to study this system. The results show that the exergy destruction rates of the two subcycles are close to the same level. The endogenous exergy destruction rate caused by the selfirreversibility of components is dominant. According to the distribution of exergy destruction rate obtained by advanced exergy analysis, the improvement strategy of combining component self-improvement, other component improvement, and system optimization for the system is presented. The three components with the highest avoidable endogenous exergy destruction rate and improvement priority are the CO 2 generator, the LiBr generator, and the turbine. This work will help to improve the exergy efficiency of the energy conversion process, and it is also of significance to the utilization of low-grade energy and the sustainable development of chemical engineering.
This study investigates a coupled system combined by a LiBr/H2O absorption refrigeration cycle and a Kalina cycle, to recover waste heat from a hydrate-based CO2 capture process. The optimal system operation has been obtained. Payback time, Return on investment, Net present value and Discounted cash flow rate of return are selected as the evaluation indicators for a comprehensive economic analysis. Cash flow patterns are obtained for different discounted interest rates and electricity prices. Exergy analysis is conducted and the exergy loss of each component is calculated. Results show that in comparison with the individual Kalina cycle, the net electricity generation is increased by around 45%. The highest thermal efficiency of this coupled system is 16.78%. Payment balance can be achieved with a payback time of 6 years. The purchase price of heat exchanger occupies the largest capital investment. Exergy efficiency of this system is obtained as 36.89%. Major system irreversibility occurs in heat transfer processes of heat exchangers and the largest exergy loss is found in generators of both subcycles. Reducing the heat transfer irreversibility and the size of heat exchangers are greatly encouraged in future efforts.
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