ANALYSIS AND OPTIMIZATION OF VAPOR ABSORPTION GENERATOR-HEAT EXCHANGER USING KERN METHOD AND CFD

The growing demand for new and eco-friendly energy resources has raised the need of sustainable sources or renewable energy for use in present era. A vapor absorption refrigeration system (VARS or VAS) is a closed loop refrigeration system which requires low heat for its functioning and, it is therefore, considered an eco-friendly solution. Since, generator is the main component of VAS which can significantly influence the efficacy of overall system, the current paper involves modeling and thermal analysis of generator using Computational Fluid Dynamics (CFD). The objective of this study is to optimize the heat transfer by changing baffle spacing of generator heat exchanger, running on a single effect LiBr/ water absorption cycle. For this purpose, hot water driven generator of 1ton capacity is taken. The simulation results of CFD were validated by comparing them with theoretical results. The overall design estimation and design technique that follows Birmingham Wire Gauge (BWG) and Tubular Exchangers Manufacturers Association (TEMA) standard are considered in this study. It was found from the analysis that the design model with smallest baffle spacing has the highest heat transfer coefficient. On reducing the baffle spacing from 137mm to 101mm, an increment of 48% in overall heat transfer coefficient was observed. Likewise, an increase in velocity by 36% and drop in static pressure by 27% were seen. Similar trend was observed in the theoretical results.

___

  • [1] S. A. Mohamed, M. N. Karimi, “Simulation of lithium bromide- water (LiBr-H2O) vapor absorption system (VAS) powered by solar flat plate collector (SFPC)”, IOP Conf. Series: Materials Science and Engineering 691 (2019) 012031, doi:10.1088/1757-899X/691/1/012031.
  • [2] C. Somers, A. Mortazavi, Y. Hwang, (2011). Modeling water/lithium bromide absorption chillers in ASPEN Plus. Applied Energy 88, 4197–4205.
  • [3] Aphornratana. S, Srikhirin. P. A review of absorption refrigeration technologies, Renew sustain energy Rev 2001: 5:343-72.
  • [5] G.A. Florides, S.A. Tassou, (2003). Design and construction of a LiBr–water absorption machine, Energy Conversion and Management 44, 2483–2508
  • [6] Siamak Hoseinzadeh, Mohammad H. Zakeri, A. Shirkhani, and Ali J. Chamkha “Analysis of energy consumption improvements of a zero-energy building in a humid mountainous area”. Journal of Renewable and Sustainable Energy. 11 (2019), doi:10.1063/1.5046512
  • [7] Ali J. Chamkha and Siamak Hoseinzadeh, Numerical investigation of rectangular thermal energy storage units with multiple phase change materials, Journal of Molecular Liquids, 271, 655-660 (2018).
  • [8] S. Hoseinzadeh, A. Moafi, A. Shirkhani and Ali J. Chamkha, “Numerical validation heat transfer of rectangular cross-section porous fins”. Journal of Thermophysics and Heat Transfer. 33, 698–704 (2019). https://doi.org/10.2514/1.T5583.
  • [9] S. Hoseinzadeh, P. S. Heyns, A. J. Chamkha and A. Shirkhani, “Thermal analysis of porous fins enclosure with the comparison of analytical and numerical methods”. Journal of Thermal Analysis and Calorimetry. 138, 727–735 (2019). https://doi.org/10.1007/s10973-019-08203-x
  • [10] Ahmed Elgafy and Osama Mesalhy and Khalid Lafdi, “Numerical study for enhancing the thermal conductivity of phase change material (PCM) storage using high thermal conductivity porous matrix”, Energy Conversion and Management 46 (2005) 847–867.
  • [11] R. Ghasemiasl, S. Hoseinzadeh, and M. A. Javad, Numerical Analysis of Energy Storage Systems Using Two Phase-Change Materials with Nanoparticles. Journal of Thermophysics and Heat Transfer. 32, 440–448 (2018). https://doi.org/10.2514/1.T5252
  • [12] Mohammad Esmaeil, Siamak Hoseinzadeh and Yousef Nezhad, Mathematical modelling and simulation of a solar water heater for an aviculture unit using MATLAB/ SIMULINK, Journal of renewable and sustainable energy 9, 063702 (2017), doi:10.1063/1.5010828.
  • [13] Siamak Hoseinzadeh and Reza Azad, Simulation and optimization of a solar-assisted heating and cooling system for a house in Northern of Iran, Journal of Renewable and Sustainable Energy. 9(2017), doi:10.1063/1.5000288.
  • [14] H. Kariman, S. Hoseinzadeh and P. Stephan Heyns, Energetic and exergetic analysis of evaporation desalination system integrated with mechanical vapor recompression circulation. Case Studies in Thermal Engineering, 100548 (2019).
  • [15] H. Kariman, S. Hoseinzadeh, A. Shirkhani, P. S. Heyns and J. Wannenburg, Energy and economic analysis of evaporative vacuum easy desalination system with brine tank. Journal of Thermal Analysis and Calorimetry. https://doi.org/10.1007/s10973-019-08945-8
  • [16] S. Hoseinzadeh, P.S. Heyns and H. Kariman, "Numerical investigation of heat transfer of laminar and turbulent pulsating Al2O3/water nanofluid flow", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. ahead-of-print No. ahead-of-print. doi.org/10.1108/HFF-06-2019-0485
  • [17] S. Hoseinzadeh, S.A.R. Sahebi, R. Ghasemiasl, and A.R. Majidian, “Experimental analysis to improving thermosyphon (TPCT) thermal efficiency using nanoparticles/based fluids (water)”. European Physical Journal Plus. 132(2017), doi:10.1140/epjp/i2017-11455-3.
  • [18] M.M. Sarafraz and M. Arjomandi, Thermal performance analysis of a microchannel heat sink cooling with copper oxide-indium (CuO/In) nano-suspensions at high-temperatures, Applied Thermal Engineering 137 (2018) 700–709.
  • [19] M. M. Sarafraz, Mohammad Reza Safaei, Zhe Tian Thermal assessment of nano-particulate graphene-water/ethylene glycol (WEG 60: 40) nano-suspension in a compact heat exchanger, Energies 2019, 12, 1929; doi:10.3390/en12101929
  • [20] M.M. Sarafraz and M.R. Safaei, Diurnal thermal evaluation of an evacuated tube solar collector (ETSC) charged with graphene nanoplatelets-methanol nano-suspension, renewable energy 142 (2019) 364- 372.
  • [21] E. Salari , S. M. Peyghambarzadeh , M.M. Sarafraz and F. Hormozi, “Boiling thermal performance of TiO2 aqueous nanofluids as a coolant on a disc copper block”, Periodica Polytechnica Chemical Engineering, DOI: 10.3311/PPch.8262
  • [22] M.M. Sarafraz, F. Hormozi, “Pool boiling heat transfer to dilute copper oxide aqueous nanofluids”, International Journal of Thermal Sciences 90 (2015) 224-237.
  • [23] Robert A. Taylor, P. Phelan, Pool boiling of nanofluids: comprehensive review of existing data and limited new data, Int. J. Heat Mass Trans. 52 (2009) 5339e5347.
  • [24] C. P. Arora 2009 Refrigeration and air conditioning, McGram- Hill book third edition.
  • [25] Theodorel. Bergman, Frank P. Incropera, 2012. Fundamentals of heat and mass transfer, MPS Limited, a Macmillan Company, Seventh Edition book.
  • [26] D. Q. Kern, Process Heat Transfer, McGraw-Hill Book Company, Int. ed. 1965.
  • [27] Mhrd, Nptel, Chemical Engineering – Chemical Engineering Design - II Joint process design of shell and tube exchanger for two phase heat transfer Joint initiative of IITs and IISc.
  • [28] Peters, M.S., Timmerhaus, K.D., and West, R.E., Plant Design and Economics for Chemical Engineers, McGraw-Hill, New York, 2003.
  • [29] A. S. Teja, S. M. Jeter, Thermophysical Property Data For Lithium Bromide/Water Solutions At Elevated Temperatures, Prepared For The American Society OF Heating, Refrigerating And Air-Conditioning Engineers Under Project 526-RP.
  • [30] L. Labra, D. Juarez-Romero, J. Siqueiros, 2016. Measurement of Properties of a Lithium Bromide Aqueous Solution for the Determination of the Concentration for a Prototype Absorption Machine, Applied Thermal Engineering, S1359-4311(16)32758 2:http://dx.doi.org.