Skip to main content

Advertisement

SpringerLink
Log in

Efficiency comparison of subcritical OTEC power cycle using various working fluids

  • Original
  • Published:
Heat and Mass Transfer Aims and scope Submit manuscript

Abstract

This paper presents an investigation into the thermal efficiency and main component size of the subcritical ocean thermal energy conversion (OTEC) power cycle using various working fluids under different operation conditions. The analysis procedure was performed with a simulation program written in Engineering Equation Solver. With the given analysis conditions, efficiencies of three types of working fluids were evaluated and compared. It was found that the thermal efficiencies of the subcritical OTEC power cycle depend strongly on the evaporating and condensing temperature, and turbine efficiency, while not roughly depending on superheating degrees and pump efficiencies. With a thorough grasp of these results, an efficient OTEC power cycle can be designed. R717 and R404A yielded the highest and lowest thermal efficiencies among the wet fluids, and R22 showed the largest efficiency among the dry fluids. For the iso-entropic fluids, R245fa provided the highest thermal efficiency. In comparison of main component sizes, R404A and R744 had the largest and smallest condenser size, respectively. Also, R744 exhibited the smallest evaporator size, and R404A and R227ea show the largest size. And R744 and R245fa gave the largest and smallest pump size, respectively. From the results of thermal efficiency and main components for various working fluids in the OTEC power cycle, R717 in the subcritical OTEC power cycle is the preferred working fluid, except for its toxicity and flammability.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

Similar content being viewed by others

Abbreviations

A:

Average (–)

cp :

Specific heat at constant pressure [J/(kg K)]

h:

Specific enthalpy (kJ/kg)

\(\Delta {\text{H}}({\text{T}}_{{{\text{t}},{\text{in}}}} )\) :

Specific enthalpy difference related to Eq. (1)

\({\text{Ja(T}}_{\text{t,in}} )\) :

Jakob number defined as \({{{\text{c}}_{\text{p}} {\text{T}}_{\text{t,in}} } \mathord{\left/ {\vphantom {{{\text{c}}_{\text{p}} {\text{T}}_{\text{t,in}} } {{\text{h}}_{\text{lv}} ( {\text{T}}_{\text{t,in}} )}}} \right. \kern-0pt} {{\text{h}}_{\text{lv}} ( {\text{T}}_{\text{t,in}} )}}\)

L:

Liquid (–)

m:

Mass flow rate (kg/s)

M:

Molecular weight (g/mol)

OTEC:

Ocean thermal energy conversion (–)

P:

Pressure (kPa, MPa)

Q:

Heat capacity (kW)

T:

Temperature (°C, K)

V:

Vapor (–)

VER:

Vapor expansion ratio (–)

W:

Power, work (kW)

\(\upeta\) :

Efficiency (–)

\(\Delta\) :

Difference (–)

\(\Delta\)h:

Latent heat (kJ/kg)

bp:

Normal boiling point

c:

Condenser, condensing

car:

Carnot

crit:

Critical

ds:

Deep seawater

e:

Evaporator, evaporating

in:

Inlet

lv:

Related to latent heat of evaporation

OTEC:

Ocean thermal energy conversion

p:

Pump

re:

Refrigerant

ss:

Surface seawater

suc:

Subcooling degree

suh:

Superheating degree

t:

Turbine

References

  1. http://en.wikipedia.org/wiki/OTEC

  2. Yoon JI, Son CH, Baek SM, Kim HJ, Lee HS (2012) Performance characteristics of R744 OTEC power cycle with operation parameters. J Korea Soc Mar Eng 36:580–585

    Article  Google Scholar 

  3. Yoon JI, Son CH, Baek SM (2012) Power system for ocean thermal energy conversion (OTEC). J Korea Soc Mar Eng 36:217–223

    Google Scholar 

  4. Bruch L (1994) Vicki, an assessment of research and development leadership in ocean energy technologies, SAND93-3946. Sandia National Laboratories, Albuquerque

    Book  Google Scholar 

  5. http://www.ioes.saga-u.ac.jp/jp/about_ocean_energy.html

  6. U.S. Energy Information Administration (2014) Average retail price of electricity to ultimate customers by end-use sector. U.S. Department of Energy, Washington

  7. Son CH, Lee DG, Oh HK, Kim YL (2004) The heat transfer and pressure drop characteristics of CO2 during supercritical region in a horizontal tube. J Korea Soc Mar Eng 28:500–508

    Google Scholar 

  8. Uehara H, Miyara A, Ikegami Y, Nakaoka T (1996) Performance analysis of an OTEC plant and a desalination plant using an integrated hybrid cycle. J Sol Energy Eng 118:115–122

    Article  Google Scholar 

  9. Uehara H, Dilao CO, Nakaoka T (1998) Conceptual design of ocean thermal energy conversion power plants in the Philippines. Sol Energy 41:431–441

    Article  Google Scholar 

  10. Yeh RH, Su TZ, Yang MS (2005) Maximum output of an OTEC power plant. Ocean Eng 32:685–700

    Article  Google Scholar 

  11. Rabas TJ, Panchal CB, Stevens HC (1990) Integration and optimization of the gas removal system for hybrid-cycle OTEC power plants. J Sol Energy Eng 112:19–28

    Article  Google Scholar 

  12. Tseng CH, Kao KY, Yang JC (1991) Optimal design of a pilot OTEC power plant in Taiwan. J Energy Resour Technol 113:294–299

    Article  Google Scholar 

  13. Kim NJ, Ng KC, Chun W (2009) Using the condenser effluent from a nuclear power plant for Ocean Thermal Energy Conversion (OTEC). Int Commun Heat Mass Transf 36:1008–1013

    Article  Google Scholar 

  14. Sun F, Ikegami Y, Jia B, Arima H (2012) Optimization design and exergy analysis of organic Rankine cycle in ocean thermal energy conversion. Appl Ocean Res 35:38–46

    Article  Google Scholar 

  15. Shengjun Z, Huaixin W, Tao G (2011) Performance comparison and parametric optimization of subcritical organic rankine cycle (ORC) and transcritical power cycle system for low-temperature geothermal power generation. Appl Energy 88:2740–2754

    Article  Google Scholar 

  16. Refrigerant report. BITZER, Germany, 15 edn, A-501-15 (2012)

  17. Klein SA (2012) Engineering Equation Solver (EES), fChart Software Inc., Academic V9.172

  18. Maizza V, Maizza A (1996) Working fluids in non-steady flows for waste energy recovery systems. Appl Therm Eng 16:579–590

    Article  Google Scholar 

  19. Chen H, Yogi Goswami D, Stefanakos K, Elias K (2010) A review of thermodynamic cycles and working fluids for the conversion of low-grade heat. Renew Sustain Energy Rev 14:3059–3067

    Google Scholar 

  20. Hung TC, Wang SK, Kuo CH, Pei BS, Tsai KF (2010) A study of organic working fluids on system efficiency of an ORC using low-grade energy sources. Energy 35:1403–1411

    Article  Google Scholar 

  21. Mikielewicz ID, Mikielewicz J (2010) A thermodynamic criterion for selection of working fluid for subcritical and supercritical domestic micro CHP. Appl Therm Eng 30:2357–2362

    Article  Google Scholar 

Download references

Acknowledgments

This work was financially supported by the National R&D project of the “Development of Energy utilization technology with Deep Ocean Water” supported by the Korean Ministry of Land, Transport and Maritime Affairs.

Author information

Authors and Affiliations

  1. Department of Refrigeration and Air-Conditioning Engineering, College of Engineering, Pukyong National University, San 100, Yongdang-dong, Nam-gu, Pusan, 608-739, South Korea

    Jung-In Yoon, Chang-Hyo Son & Seung-Moon Baek

  2. Deep Ocean Water Application Research Center, Korea Ocean Research and Development Institute, 245-7 Oho-ri, Jukwang-myeon, Goseong-gun, Gangwon-do, 219-822, South Korea

    Hyeon-Ju Kim & Ho-Saeng Lee

Authors
  1. Jung-In Yoon
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Chang-Hyo Son
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Seung-Moon Baek
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Hyeon-Ju Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Ho-Saeng Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Chang-Hyo Son.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Yoon, JI., Son, CH., Baek, SM. et al. Efficiency comparison of subcritical OTEC power cycle using various working fluids. Heat Mass Transfer 50, 985–996 (2014). https://doi.org/10.1007/s00231-014-1310-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00231-014-1310-8

Keywords

Search

Navigation