Multi-objective Optimization of a Two-bed Solar Adsorption Chiller based on Exergy and Economics

In this present work, a two-bed solar adsorption chiller is simulated and optimized. This system uses two working-pair candidates, namely silica gel-water and zeolite-water. Optimization using a multi-objective genetic algorithm was conducted to find out the optimum condition of the system in terms of a thermodynamic analysis and an economic point of view. Exergy destruction and total annual costs were the two objective functions examined while solar collector area, cooling water mass flow rate, hot water mass flow rate, and chilled water mass flow rate were chosen as decision variables for optimizing the procedure. The results show that the zeolite-water working pair had a lower value of exergy destruction and annual cost compared to the silica gel-water working pair, which resulted in an exergy destruction of 150,938 watts at annual cost of $216,818 USD. However, the zeolite-water working pair had a lower cooling capacity and coefficient of performance (COP) than the silica gel-water working pair.

Adsorption chiller; Economics; Exergy; Multi-objective Optimization; Solar

Vapor-compression cycles in HVAC systems usually contain chlorofluorocarbon and hydrochlorofluorocarbon. Some refrigerants with high global warming potential and ozone depletion potential values have contributed to ozone layer depletion and global warming (Nasruddin et al., 2015). Therefore, an alternative refrigeration system is required. Such alternative cooling and refrigeration technology, known as an adsorption system, exists that is driven by renewable energy sources (Wang et al., 2009). In recent decades, adsorption cooling and refrigeration systems driven by solar energy have attracted increased attention because they can change heat from solar radiation into cool air without using any environmentally harmful refrigerants (Luo et al., 2007; Xua, 2012).

Besides the environmental benefits, adsorption cooling systems have many advantages (Sumathy et al., 2003; Wang & Oliveira, 2006); they use natural refrigerants like water, they lack a vibration effect, they are simple to construct and control, they use low grade heat source temperatures, they lack of moving parts, and their operating costs are low. In addition, compared to other cooling systems, the adsorption system shows no problems with corrosion of materials or substance crystallization.

The need for optimum adsorption cooling systems encourages researchers to search for possible way to improve the system. Some research has focused on the physicochemical properties of different adsorbent-adsorbate (Wang et al., 2004; Wang et al., 2009;). Miyazaki et al. (2009) examined a new cycle time allocation to increase the adsorption system performance. Miyazaki and Akisawa (2009) optimized the effect heat capacity and number of transfer units (NTU) of adsorption cooling systems. Boelman et al. (1995) studied the effect of operating conditions on COP and cooling capacity in adsorption cooling systems. Wang et al. (2009) investigated adsorption chillers using working pairs and varieties of heat sources. Saha et al. (1995) simulated a model to analyze the operating conditions of adsorption cooling systems with two-bed silica gel. Pan et al. (2014) examined the use of a modular-type adsorbent that can greatly reduce manufacturing costs. Nasruddin et al. (2016) simulated a silica gel-water solar adsorption chiller based in the climatic condition of a tropical country. From of all research conducted by the researchers above, it has provided a comprehensive conception of how to optimize the performance of the adsorption chiller from the cycle of system and the development of the adsorbent.

This study aims to simulate and analyze the configurations of a two-bed solar adsorption chiller by applying thermo-economic analysis. In addition, software is also used to perform multi-objective optimization by using multi-objective genetic algorithm. A thermo-economic approach is conducted to find out the optimum condition in terms of thermodynamic analysis and from an economic point of view.

In this study, a configuration of the a two-bed solar adsorption chiller is simulated and optimized using Matlab software. To determine the system performance from a thermodynamic and economic point of view, a thermoeconomic analysis was performed with exergy destruction and annual costs as objective functions of this analysis The results showed that by comparing the working pairs of water-silica gel with zeolite-water, the zeolite-water working pair had a lower value of exergy destruction and annual cost.  However, the cooling capacity and COP of zeolite-water working pair has a lower value of than the silica gel-water working pair.

The authors gratefully acknowledge the financial support that provide by DRPM – Universitas Indonesia for PITTA research grant under Contract No: 2497/UN.R3.1/HKP.05.00/2018. 

AlZahrani, A.A., Dincer, I., 2018. Energy and Exergy Analyses of a Parabolic trough Solar Power Plant using Carbon Dioxide Power Cycle. Energy Conversion and Management, Volume 158, pp. 476–488

Bejan, A., Kraus, A.D., 2003. Heat Transfer Handbook. Volume 1. John Wiley & Sons, USA

Bejan, A., Tsatsaronis, G., Moran, M., 1996. Thermal Design and Optimization, John Wiley & Sons, USA

Bindra, H., Bueno, P., Morris, J.F., 2014. Sliding Flow Method for Exergetically Efficient Packed Bed Thermal Storage. Applied Thermal Engineering, Volume 64(1-2), pp. 201–208

Boelman, E.C., Saha, B.B., Kashiwagi, T., 1995. Experimental Investigation of a Silica Gel-water Adsorption Refrigeration Cycle—The Influence of Operating Conditions on Cooling Output and COP. Unknown Journal, Volume 101, pp. 358–366

Feng, H., Chen, L., Liu, X., Xie, Z., Sun, F., 2016. Constructal Optimization of a Sinter Cooling Process based on Exergy Output Maximization. Applied Thermal Engineering, Volume 96, pp. 161–166

Luo, H.L., Wang, R.Z., Dai, Y.J., Wu, J.Y., Shen, J.M., Zhang, B.B., 2007. An Efficient Solar-powered Adsorption Chiller and Its Application in Low-temperature Grain Storage. Solar Energy, Volume 81(5), pp. 607–613

Miyazaki, T., Akisawa, A., 2009. The Influence of Heat Exchanger Parameters on the Optimum Cycle Time of Adsorption Chillers. Applied Thermal Engineering, Volume 29(13), pp. 2708–2717

Miyazaki, T., Akisawa, A., Saha, B.B., El-Sharkawy, I.I., Chakraborty, A., 2009. A New Cycle Time Allocation for Enhancing the Performance of Two-bed Adsorption Chillers. International Journal of Refrigeration, Volume 32(5), pp. 846–853

National Institute of Standards and Technology (NIST), 1998. NIST Standard Reference Database 23: NIST Thermodynamic and Transport Properties of Refrigerants and Refrigerant Mixtures—REFPROP. U.S. Department of Commerce, Gaithersburg, Maryland

Nasruddin, Alamsyah, D., Budiman, D., Ericsson, J., 2016. The Effect of Zeolite Adsorbent Granular Size on Solar Adsorption Chiller for Universitas Indonesia Area. International Journal of Technology, Volume 7(2), pp. 254–263

Nasruddin, Lemington, Alhamid, M.I., 2015. Numerical Simulation of a Two-bed Solar-driven Adsorption Chiller in a Tropical Climate. International Journal of Technology, Volume 6(4), pp. 594-603

Nasruddin, Nasution, S., Aisyah, N., Surachman, A., Wibowo, A.S., 2018. Exergy Analysis and Exergoeconomic Optimization of a Binary Cycle System using a Multi Objective Genetic Algorithm. International Journal of Technology, Volume 9(2), pp. 275–286

Pan, Q.W., Wang, R.Z., Wang, L.W., Liu, D., 2014. Design and Experimental Study of Adsorption Chiller with Module Type Adsorber. In: Proceedings of the International Conference of Solar Heating and Cooling for Building and Industry, SHC

Rezayan, O., Behbahaninia, A., 2011. Thermoeconomic Optimization and Exergy Analysis of CO₂/NH₃ Cascade Refrigeration Systems. Energy, Volume 36(2), pp. 888–895

Saha, B.B., Boelman, E.C., Kashiwagi, T., 1995. Computational Analysis of an Advanced Adsorption-refrigeration Cycle. Energy, Volume 20(10), pp. 983–994

Shah, R.K., Sekulic, D.P., 2003. Fundamentals of Heat Exchanger Design, John Wiley & Sons, USA

Shojaeizadeh, E., Veysi, F., 2016. Development of a Correlation for Parameter Controlling using Exergy Efficiency Optimization of an Al₂O₃/Water Nanofluid Based Flat-plate Solar Collector. Applied Thermal Engineering, Volume 98, pp. 1116–1129

Singh, K., Das, R., 2017. Exergy Optimization of Cooling Tower for HGSHP and HVAC Applications. Energy Conversion and Management, Volume 136, pp. 418–430

Smith R., 2005. Chemical Process: Design and Integration, John Wiley & Sons, USA

Sumathy, K., Yeung, K.H., Yong, L., 2003. Technology Development in the Solar Adsorption Refrigeration Systems. Progress in Energy and Combustion Science, Volume 29(4), pp. 301–327

Wang, R.Z., Oliveira, R.G., 2006. Adsorption Refrigeration—An Efficient Way to Make Good Use of Waste Heat and Solar Energy. Progress in Energy and Combustion Science, Volume 32(4), pp. 424–458

Wang, L.W., Wang, R.Z., Wu, J.Y., Wang, K., Wang, S.G., 2004. Adsorption Ice Makers for Fishing Boats Driven by the Exhaust Heat from Diesel Engine: Choice of Adsorption Pair. Energy Conversion and Management, Volume 45(13-14), pp. 2043–2057

Wang, L.W., Wang, R.Z., Oliveira, R.G., 2009. A Review on Adsorption Working Pairs for Refrigeration. Renewable and Sustainable Energy Reviews, Volume 13(3), pp. 518–534

Xua, S., 2012. Experiment on a New Adsorption Refrigeration Driven by Solar Energy. Energy Procedia, Volume 14, pp. 1542–1547