Analyses of mixed-hydrocarbon binary thermodynamic cycles for moderate-temperature geothermal resources using regeneration techniques

Demuth, O.J.; Kochan, R.J.

doi:10.2172/5281969

Cited by 9 publications

(12 citation statements)

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“…Previously published work [21] has investigated different types of multi-component mixtures comprising hydrocarbons, hydrofluorocarbons or siloxanes together with important mixture performance measures and constraints that need to be considered for their evaluation. Hydrocarbon mixtures were also proposed considering regenerative preheating ORC schemes [22], equipment sizing [23] and zeotropic fluids [24] for efficient exploitation of moderate temperature geothermal resources. Mixtures of siloxanes or hydrocarbons have been considered [25] to recover wasted heat from molten carbonate fuel cells using an ORC.…”

Section: Working Fluid Selection Applicationsmentioning

confidence: 99%

Systematic Methods for Working Fluid Selection and the Design, Integration and Control of Organic Rankine Cycles—A Review

2015

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Efficient power generation from low to medium grade heat is an important challenge to be addressed to ensure a sustainable energy future. Organic Rankine Cycles (ORCs) constitute an important enabling technology and their research and development has emerged as a very active research field over the past decade. Particular focus areas include working fluid selection and cycle design to achieve efficient heat to power conversions for diverse hot fluid streams associated with geothermal, solar or waste heat sources. Recently, a number of approaches have been developed that address the systematic selection of efficient working fluids as well as the design, integration and control of ORCs. This paper presents a review of emerging approaches with a particular emphasis on computer-aided design methods.

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Section: Working Fluid Selection Applicationsmentioning

confidence: 99%

Systematic Methods for Working Fluid Selection and the Design, Integration and Control of Organic Rankine Cycles—A Review

2015

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“…In this manner, the evaporator load is significantly reduced, and the efficiency of the cycle is extensively improved (Fig. 1b) [18,19].…”

Section: Proposed Modelmentioning

confidence: 99%

Thermodynamic analysis and performance optimization of organic rankine cycles for the conversion of low-to-moderate grade geothermal heat

Yekoladio

Bello‐Ochende

Meyer

2015

Int. J. Energy Res.

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The present study considers a thermodynamic analysis and performance optimization of geothermal power cycles. The proposed binary-cycles operate with moderately low temperature and liquid-dominated geothermal resources in the range of 110 o C to 160 o C, and cooling air at ambient conditions of 25 o C and 101.3 kPa reference temperature and atmospheric pressure, respectively. A thermodynamic optimization process and irreversibility analysis were performed to maximize the power output while minimizing the overall exergy destruction and improving the First-and Second-law efficiencies of the cycle. Maximum net power output was observed to increase exponentially with the geothermal resource temperature to yield 16-49 kW per unit mass flow rate of the geothermal fluid for the nonregenerative ORCs, as compared to 8-34 kW for the regenerative cycles. The cycle First-law efficiency was determined in the range of 8-15% for the investigated geothermal binary power cycles. Maximum Second-law efficiency of approximately 56% was achieved by the ORC with an IHE. In addition, a performance analysis of selected pure organic fluids such as R123, R152a, isobutane and n-pentane, with boiling points in the range of -24 o C to 36 o C, was conducted under saturation temperature and subcritical pressure operating conditions of the turbine. Organic fluids with higher boiling point temperature, such as n-pentane, were recommended for non-regenerative cycles. The regenerative ORCs, however, require organic fluids with lower vapour specific heat capacity (i.e. isobutane) for an optimal operation of the binary-cycle.

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“…Thus, the 34°F cold end approach used in this study, so as to better compare results with the commercial isobutane cases, is optimal or near optimal. As noted earlier, a 10°F cold end approach has been used in previous studies on counterflow water-cooled mixed fluid binary cycles (Demuth, 1982;Bliem and Mines, 1993). For the Surprise Valley resource, a 10°F cold end approach leads to a temperature cross in the aircooled condenser, and a feasible air cooler design cannot be obtained.…”

Section: -5mentioning

confidence: 99%

“…Prior studies have suggested that using mixtures of hydrocarbons instead of pure components in binary cycles will enhance the cycle's specific output (Demuth, 1982;Bliem and Mines, 1993). In this section of the report the evaluation of binary cycles with mixed working fluids is presented.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Next Generation Geothermal Power Plants

Brugman¹,

Hattar²,

Nichols³

et al. 1995

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Analyses of mixed-hydrocarbon binary thermodynamic cycles for moderate-temperature geothermal resources using regeneration techniques

Cited by 9 publications

References 0 publications

Systematic Methods for Working Fluid Selection and the Design, Integration and Control of Organic Rankine Cycles—A Review

Systematic Methods for Working Fluid Selection and the Design, Integration and Control of Organic Rankine Cycles—A Review

Thermodynamic analysis and performance optimization of organic rankine cycles for the conversion of low-to-moderate grade geothermal heat

Next Generation Geothermal Power Plants

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