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Influence of working fluid evaporation temperature in the near-critical point region on the effectiveness of ORC power plant operation

Władysław Nowak Aleksandra Borsukiewicz-Gozdur Sławomir Wiśniewski
Archives of Thermodynamics | 2012 | No 3 October | 73-83 | DOI: 10.2478/v10173-012-0019-7
Keywords ORC Binary power plants Near-critical region Working fluid
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Abstract

In the paper presented are definitions of specific indicators of power which characterize the operation of the organic Rankine cycle (ORC) plant. These quantities have been presented as function of evaporation temperature for selected working fluids of ORC installation. In the paper presented also is the procedure for selection of working fluid with the view of obtaining maximum power. In the procedure of selection of working fluid the mentioned above indicators are of primary importance. In order to obtain maximum power there ought to be selected such working fluids which evaporate close to critical conditions. The value of this indicator increases when evaporation enthalpy decreases and it is known that the latent heat of evaporation decreases with temperature and reaches a value of zero at the critical point.
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Authors and Affiliations

Władysław Nowak
Aleksandra Borsukiewicz-Gozdur
Sławomir Wiśniewski

Challenges in operating and testing loop heat pipes in 500–700 K temperature ranges

Paweł Szymański Dariusz Mikielewicz
Archives of Thermodynamics | 2022 | vol. 43 | No 2 | 61-73 | DOI: 10.24425/ather.2022.141978
Keywords Loop heat pipe Working fluid Material compatibility
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Abstract

The potential applications of loop heat pipes (LHPs) are the nuclear power space systems, fuel cell thermal management systems, waste heat recovery systems, medium temperature electronic systems, medium temperature military systems, among others. Such applications usually operate in temperature ranges between 500–700 K, hence it is necessary to develop an LHP system that will meet this requirement. Such a thermal management device require to meet various technical problems and challenges currently existing in the development of LHP working in medium temperatures, including: (1) selection of appropriate working fluid; (2) selection of appropriate LHP construction material; (3) construction of suitable test rig capable of testing at elevated temperatures; (4) development of new testing methods. Currently, there are no proven working fluids that can be used in LHPs in medium temperature ranges. Water can be applicable only at temperatures up to 570 K. Caesium can be applicable at temperatures above 670 K. Organic fluids usually tend to generate non-condensable gasses and/or decompose at elevated temperatures and their viscosity dramatically increases. For halides, most of them are very reactive or toxic and their full property data are not available or the majority of the physical properties are predicted, also live tests and their environmental impact data are not adequate. As for casing/LHP construction material, there are no full chemical compatibility tables with most of the medium temperature working fluids and the reactivity of fluids significantly limits the potential materials. Also, testing such an LHP is an endeavour as the reactivity of medium temperature fluids and the use of obscure metals create new challenges. Altogether creates multiple challenges in the development, testing, handling and operating of LHP in the medium temperature range.
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Bibliography

[1] Zohuri B.: Heat Pipe Design and Technology. Modern Applications for Practical Thermal Management (2nd Edn.). Springer, 2016.
[2] Zhang Y. (Ed.): Heat Pipes: Design, Applications and Technology. Nova, 2018.
[3] Anderson W.G., Bland J.J., Fershtater Y., Goncharov K.A., Nikitkin M., Juhasz A.: High-temperature loop heat pipes. IECEC AP-18, ASME 1995.
[4] Anderson W.G., Rosenfeld J.H., Angirasa D., Mi Y.: Evaluation of heat pipe working fluids in the temperature range 450 to 700 K. AIP Conf. Proc. 699(2004), 20.
[5] Anderson W.G., Bienert W.: Loop heat pipe radiator trade study for the 300– 550 K temperature range. AIP Conf. Proc. 746(2005), 946.
[6] Anderson W.G.: Intermediate temperature fluids for heat pipes and loop heat pipes. In: Proc. 5th Int. Energy Conversion Engineering Conf. Exhib. (IECEC), 25–27 June 2007, AIAA 2007–4836.
[7] Faghri A., Buchko M., Cao Y.: A study of high-temperature heat pipes with multiple heat sources and sinks: Part I – Experimental methodology and frozen startup profiles. J. Heat Transf. 113(1991), 4, 1003–1009.
[8] Faghri A., Buchko M., Cao Y.: A study of high-temperature heat pipes with multiple heat sources and sinks: Part II – Analysis of continuum transient and steadystate experimental data with numerical predictions. J. Heat Transf. 113(1991), 4, 1010–1016.
[9] https://www.1-act.com/merit-number-and-fluid-selection/ (accessed 10 Sept. 2021).
[10] NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP), Version 10. https://www.nist.gov/srd/refprop/ (accessed 10 Sept. 2021).
[11] Blauciak K., Szymanski P., Mikielewicz D.: The influence of loop heat pipe evaporator porous structure parameters and charge on its effectiveness for ethanol and water as working fluids. Materials 14(2021), 7029.
[12] Nikitkin M.N., Bienert W.B., Goncharov K.A.: Non condensable gases and loop heat pipe operation. SAE Tech. Pap. 981584. In: Proc. 28th Int. Conf. on Environmental Systems, 1998.
[13] Wrenn K.R., Wolf D., Kroliczek E.J.: Effect of non-condensible gas and evaporator mass on loop heat pipe performance. SAE Tech. Pap. 2000-01-2409. In: Proc. 30th Int. Conf. on Environmental Systems, 603–614, 2000.
[14] Ishikawa H., Ogushi T., Nomura T., Noda H., Kawasaki H., Yabe T.: Heat transfer characteristics of a reservoir embedded loop heat pipe (2nd report, influence of noncondensable gas on heat transfer characteristics). Heat Transf. Asian Res. 36(2007), 8, 459–473.
[15] Singh R., Akbarzadeh A., Mochizuki M.: Operational characteristics of the miniature loop heat pipe with non-condensable gases. Int. J. Heat Mass Tran. 53(2010), 17–18, 3471–3482.
[16] He J., Lin G., Bai L., Miao J., Zhang H.: Effect of non-condensable gas on the operation of a loop heat pipe. Int. J. Heat Mass Tran. 70(2014), 449–462.
[17] Prado-Montes P.: Development of an elevated temperature loop heat pipe for space applications and investigation of non-condensable gas impact on its performance. PhD thesis, Polytechnic University of Madrid, Madrid 2014.
[18] Devarakonda A., Xiong D., Beach E.D.: Intermediate temperature water heat pipe tests. AIP Conf. Proc. 746(2005), 158.
[19] Mishkinis D., Prado P., Sanz R., Radkov A., Torres A., Tjiptajardja T.: Loop heat pipe working fluids for intermediate temperature range: from –40°C to +125°C. In: Proc. 1st. Int. Conf. on Heat Pipes for Space Applications, Moscow, Sept. 2009.
[20] Mikielewicz D, Błauciak K.: Investigation of the influence of capilary effect on operation of the loop heat pipe. Arch. Thermodyn. 35(2014), 3, 59–80.
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Authors and Affiliations

Paweł Szymański
1
Dariusz Mikielewicz
1
  1. Gdansk University of Technology, Faculty of Mechanical Engineering and Ship Technology, Narutowicza 11/12,80-233 Gdansk, Poland

COMPARATIVE ANALYSIS OF EFFECIENCY OF WASTE HEAT CONVERSION IN LOW-TEMPERATURE BRAYTON CYCLE

Aleksandra Borsukiewicz Piotr Stawicki
Chemical and Process Engineering | 2018 | vol. 39 | No 1
Keywords Brayton cycle working fluid low temperature source low temperature power plant
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Abstract

The paper discusses the feasibility, effectiveness and validity of a gas turbine power plant, operated according to the Brayton comparative cycle in order to develop low-potential waste heat (160◦C) and convert it into electricity. Fourteen working fluids, mainly with organic origin have been examined. It can be concluded that low molecular weight working fluids allow to obtain higher power efficiency of Brayton cycle only if conversions without taking into account internal losses are considered. For the cycle that takes into account the compression conversion efficiency in the compressor and expansion in the gas turbine, the highest efficiency was obtained for the perfluoropentane working medium and other substances with relatively high molecular weight values. However, even for the cycle using internal heat recovery, the thermal efficiency of the Brayton cycle did not exceed 7%.The paper discusses the feasibility, effectiveness and validity of a gas turbine power plant, operated according to the Brayton comparative cycle in order to develop low-potential waste heat (160◦C) and convert it into electricity. Fourteen working fluids, mainly with organic origin have been examined. It can be concluded that low molecular weight working fluids allow to obtain higher power efficiency of Brayton cycle only if conversions without taking into account internal losses are considered. For the cycle that takes into account the compression conversion efficiency in the compressor and expansion in the gas turbine, the highest efficiency was obtained for the perfluoropentane working medium and other substances with relatively high molecular weight values. However, even for the cycle using internal heat recovery, the thermal efficiency of the Brayton cycle did not exceed 7%.
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Authors and Affiliations

Aleksandra Borsukiewicz
Piotr Stawicki

Experimental investigation of gravity-assisted wickless heat pipes (thermosyphons) at low heat inputs for solar application

Hassan Naji Salman Al-Joboory
Archives of Thermodynamics | 2020 | vol. 41 | No 2 | 257-276 | DOI: 10.24425/ather.2020.133632
Keywords Wickless heat pipe Adiabatic section Solar heat pipe Fill charge ratio Working fluid inventory Inclination angle
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Abstract

The performance of ten wickless heat pipes without adiabatic sections is investigated experimentally at low heat inputs 120 to 2000 W/m2 for use in solar water heaters. Three heat pipe diameter groups were tested, namely 16, 22, and 28.5 mm. Each group had evaporator lengths of 1150, 1300, and 1550 mm, respectively, with an extra evaporator length of 1800 mm added to the second group. The condenser section length of all heat pipes was 200 mm. Ethanol, methanol, and acetone were utilized as working fluids, at inventory of 25%, 50%, 70%, and 90% by evaporator volume respectively. The 22 mm diameter pipes were tested at inclination angles 30◦, 45◦, and 60◦. Other diameter groups were tested at 45◦ only. Experiments revealed increased surface temperatures and heat transfer coefficients with increased pipe diameter and evaporator length, and that increased working fluid inventory caused pronounced reduction in evaporator surface temperature accompanied by improved heat transfer coefficient to reach maximum values at 50% inventory for the selected fluids. Violent noisy shocks were observed with 70% and 90% inventories with the tested heat pipes and the selected working fluids with heat flux inputs from 320–1900 W/m2. These shocks significantly affected the heat pipes heat transfer capability and operation stability. Experiments revealed a 45◦ and 50% optimum inclination angle of fill charge ratio respectively, and that wickless heat pipes can be satisfactorily used in solar applications. The effect of evaporator length and heat pipe diameter on the performance was included in data correlations.

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Authors and Affiliations

Hassan Naji Salman Al-Joboory

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