Energy and exergy recovery from exhaust hot water using organic Rankine cycle and a retrofitted configuration

Abstract

Exhaust hot water (EHW) is widely used for various industrial processes. However, the excess heat carried by EHW is typically ignored and discharged into the environment, resulting in heat loss and heat pollution. An organic Rankine cycle (ORC) is an attractive technology to recycle heat from low-temperature energy carriers. Herein, ORC was used to recycle the heat carried by EHW. To investigate the energy and exergy recovery effects of EHW, a mathematical model was developed and a parametric study was conducted. The energy efficiency and exergy efficiency of the EHW-driven ORC system were modeled with R245fa, R113 and R123 as the working fluids. The results demonstrate that the EHW and evaporation temperatures have significant effects on the energy and exergy efficiencies of the EHW-driven ORC system. Under given EHW conditions, an optimum evaporation temperature exists corresponding to the highest exergy efficiency. To further use the low-temperature EHW, a configuration retrofitted to the ORC by combining with flash evaporation (FE) was conducted. For an EHW at 120 °C and 0.2 MPa, the maximum exergy efficiency of the FE-ORC system is 45.91% at a flash pressure of 0.088 MPa. The FE-ORC performs better in exergy efficiency than the basic FE and basic EHW-driven ORC.

Keywords

exhaust hot water (EHW) / organic Rankine cycle (ORC) / energy efficiency / exergy efficiency / flash evaporation (FE)

References

[1] LvZ Q, CaiJ, SunW Q, LiuC. Application of vacuum distillation to treat wastewater coming from hot rolling process [J]. Journal of Residuals Science and Technology, 2016, 13: S75-S80

[2] SunW Q, ZhaoZ Q, WangY H. Thermal analysis of a thermal energy storage unit to enhance a workshop heating system driven by industrial residual water [J]. Energies, 2017, 10(2): 219

[3] LiY M, XiaJ J, FangH, SuY B, JiangY. Case study on industrial surplus heat of steel plants for district heating in Northern China [J]. Energy, 2016, 102: 397-405

[4] DziedzicR, KarneyB W. Energy metrics for water distribution system assessment: Case study of the Toronto network [J]. Journal of Water Resources Planning and Management, 2015, 141(11): 04015032

[5] RogersJ E. Energy efficiency: The fifth fuel [J]. Electric Perspectives, 2007, 32288

[6] MauludaA L, SaidiH. The Malaysian fifth fuel policy: Re-strategising the Malaysian renewable energy initiatives [J]. Energy Policy, 2012, 4888-92

[7] TogawaT, FujitaT, DongL, FujiiM, OobaM. Feasibility assessment of the use of power plant-sourced waste heat for plant factory heating considering spatial configuration [J]. Journal of Cleaner Production, 2014, 8160-69

[8] WangZ Q, ZhouQ Y, XiaX X, LiuB, ZhangX. Performance comparison and analysis of a combined power and cooling system based on organic Rankine cycle [J]. Journal of Central South University, 2017, 24(2): 353-359

[9] SunW Q, YueX Y, WangY H. Exergy efficiency analysis of ORC (Organic Rankine Cycle) and ORC-based combined cycles driven by low-temperature waste heat [J]. Energy Conversion and Management, 2017, 135: 63-73

[10] ChenC L, LiP Y, LeS N T. Organic Rankine cycle for waste heat recovery in a refinery [J]. Industrial & Engineering Chemistry Research, 2016, 55: 3262-3275

[11] KosmadakisG, ManolakosD, KyritsisS, PapadakisG. Simulation of an autonomous, two-stage solar organic Rankine cycle system for reverse osmosis desalination [J]. Desalination and Water Treatment, 2009, 1: 114-127

[12] Delgado-TorresA M, Garcia-RodriguezL. Analysis and optimization of the low-temperature solar organic Rankine cycle (ORC) [J]. Energy Conversion and Management, 2010, 51: 2846-2856

[13] Bryszewska-MazurekA ŚWIEBODA T, MAZUREK W T M W. Performance analysis of a solar-powered organic Rankine cycle engine [J]. Journal of the Air & Waste Management Association, 2011, 61(1): 3-6

[14] SchusterA, KarellasS, KakarasE, SpliethoffH. Energetic and economic investigation of organic Rankine cycle applications [J]. Applied Thermal Engineering, 2009, 29: 1809-1817

[15] FiaschiD, LifshitzA, ManfridaG, TempestiD. An innovative ORC power plant layout for heat and power generation from medium-to low-temperature geothermal resources [J]. Energy Conversion and Management, 2014, 88: 883-893

[16] LuoX, WangY, ZhaoJ, ChenY, MoS, GongY. Grey relational analysis of an integrated cascade utilization system of geothermal water [J]. International Journal of Green Energy, 2016, 13(1): 14-27

[17] IgoboO N, DaviesP A. Low-temperature organic Rankine cycle engine with isothermal expansion for use in desalination [J]. Desalination and Water Treatment, 2015, 55: 3694-3703

[18] DaviesP A, OrfiJ. Self-powered desalination of geothermal saline groundwater: Technical feasibility [J]. Water, 2014, 6: 3409-3432

[19] XiaoS, WuS Y, ZhengD S. Slag-washing water of blast furnace power station with supercritical organic Rankine cycle [J]. Journal of Central South University, 2013, 20(3): 737-741

[20] GuoC, DuX Z, YogiG D, YangL J. Investigation on working fluids selection for organic Rankine cycles with low-temperature heat sources [J]. International Journal of Green Energy, 2016, 13(6): 556-565

[21] BaralS, KimK C. Thermodynamic modeling of the solar organic Rankine cycle with selected organic working fluids for cogeneration [J]. Distributed Generation & Alternative Energy Journal, 2014, 29(3): 7-34

[22] MagoP J, ChamraL M, SomayajiC. Performance analysis of different working fluids for use in organic Rankine cycles [J]. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power & Energy, 2007, 221: 255-263

[23] HungT C, WangS K, KuoC H, PeiB S, TsaiK F. A study of organic working fluids on system efficiency of an ORC using low-grade energy sources [J]. Energy, 2010, 35(3): 1403-1411

[24] KarellasS, SchusterA. Supercritical fluid parameters in organic Rankine cycle applications [J]. International Journal of Thermodynamics, 2008, 11(3): 101-108

[25] WangZ, ZhouN, LuoL, ZhangJ, TongDao. Comparison of thermodynamic performance for waste heat power generation system with different low temperature working fluids [J]. Journal of Central South University: Science and Technology, 2010, 41(6): 2424-2429

[26] PierobonL, RokniM. Thermodynamic analysis of an integrated gasification solid oxide fuel cell plant with a Kalina cycle [J]. International Journal of Green Energy, 2015, 12(6): 610-619

[27] WeiL, ZhangY, MuY, YangX, ChenX. Efficiency improving strategies of low-temperature heat conversion systems using organic Rankine cycles: An overview [J]. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2011, 33(9): 869-878

[28] MagoP J. Exergetic evaluation of an organic Rankine cycle using medium-grade waste heat [J]. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2012, 34(19): 1768-1780

[29] SpaydeE, MagoP J. Evaluation of a solar-powered organic Rankine cycle using dry organic working fluids [J]. Cogent Engineering, 2015, 2: 1085300

[30] KhennichM, GalanisN. Thermodynamic analysis and optimization of power cycles using a finite low-temperature heat source [J]. International Journal of Energy Research, 2011, 36(7): 871-885

[31] WangZ Q, ZhouN J, ZhangJ Q, GuoJ, WangX Y. Parametric optimization and performance comparison of organic Rankine cycle with simulated annealing algorithm [J]. Journal of Central South University, 2012, 19(9): 2584-2590

[32] WuS Y, JiangL, XiaoL, LiY R, XuJ L. An investigation on the exergo-economic performance of an evaporator in orc recovering low-grade waste heat [J]. International Journal of Green Energy, 2012, 9(8): 780-799

[33] WuS Y, ZhouS M, XiaoL. The determination and matching analysis of pinch point temperature difference in evaporator and condenser of organic Rankine cycle for mixed working fluid [J]. International Journal of Green Energy, 2016, 13(5): 470-480

[34] WangH, PetersonR, HerronT. Design study of configurations on system COP for a combined ORC (organic Rankine cycle) and VCC (vapor compression cycle) [J]. Energy, 2011, 364809-4820

[35] SunW, ZhangF. Design and thermodynamic analysis of a flash power system driven by process heat of continuous casting grade steel billet [J]. Energy, 2016, 116: 94-101

[36] MansourM K, FathH E S. Numerical simulation of flashing process in MSF flash chamber [J]. Desalination and Water Treatment, 2013, 51: 2231-2243

[37] RoyJ P, MishraM K, MisraA. Parametric optimization and performance analysis of a regenerative organic Rankine cycle using low-grade waste heat for power generation [J]. International Journal of Green Energy, 2011, 8(2): 173-196

[38] SalehB, KoglbauerG, WendlandM, FischerJ. Working fluids for low-temperature organic Rankine cycles [J]. Energy, 2007, 32(7): 1210-1221

[39] AndersenW C, BrunoT J. Rapid screening of fluids for chemical stability in organic Rankine cycle applications [J]. Industrial & Engineering Chemistry Research, 2005, 44: 5560-5566