scholarly journals Exergy and economic assessments of an organic rankine cycle module designed for heat recovery in commercial truck engines

2020 ◽  
Vol 13 (37) ◽  
pp. 3871-3883
Author(s):  
Julius Thaddaeus ◽  

Objectives: To evaluate the energy and exergy performances of a designed ORC system and to quantify loses within the system and measure its output.The study also assesses the economic performance of the ORC system to determine the feasibility of the business. Methods: Thermodynamic analysis assessing the energy performance and cost estimation using manufacturers’ prices to generate generic equations for estimating costs of the components of the designed ORC system. Findings: The results of the exergy evaluation of the ORC show a system thermal efficiency of 6.39%, net power output of 3.10kWe, exergy destruction of 9.07kW, and exergy efficiency of 54.6%. The economic estimation has a capital investment cost of £8,381.98, a specific investment cost of £2,754.36/kWe, annual savings of £1,233.34, and a payback period of 6.8years. Novelty: The use of exergetic method of analysis and the assessment of the potential economic benefits of installing the module in commercial trucks which form part of the acceptance-criteria, using prevailing market prices of the ORC system is an obvious novelty in this study. In addition, the generation and use of curve-fitting plots to obtain the generic equations for computing the approximate costs of the individual components of the system is an integral part of the novelty of this work. Keywords: Organic Rankine cycle; exergy and economic assessment; specific investment cost; capital investment cost; payback period; exhaust heat recovery

Author(s):  
Quazi E. Hussain ◽  
David R. Brigham

The Rankine cycle is used commercially to generate power in stationary power plants using water as the working fluid. For waste heat recovery applications, where the temperature is lower, water is typically replaced by a carefully selected organic fluid. This work is based on using the waste heat in an automobile to generate electricity using the Organic Rankine cycle (ORC) with R245fa (1, 1, 1, 3, 3 penta-fluoropropane) as the working fluid. The electricity thus generated can be used to drive the accessory load or charge the battery which in any case helps improve the fuel economy. A simple transient numerical model has been developed that is capable of capturing the main effects of this cycle. Results show that exhaust heat alone can generate enough electricity that is capable of bringing about an improvement to the fuel economy under transient drive cycle conditions. Power output during EPA Highway drive cycle is much higher than EPA City due to higher exhaust mass flow rate and temperature. Time needed to reach operating conditions or in other words, the warm-up time plays an important role in the overall drive cycle output. Performance is found to improve significantly when coolant waste heat is used in conjunction with the residual exhaust heat to pre-heat the liquid. A sizing study is also performed to keep the cost, weight, and packaging requirement down without sacrificing too much power. With careful selection of heat exchanger design parameters, it has been demonstrated that the backpressure on the engine can be actually lowered by cooling off the exhaust gas. This lower backpressure will further boost the fuel economy gained by the electricity produced by the Rankine bottoming cycle.


2017 ◽  
Vol 11 (4) ◽  
pp. 527-534 ◽  
Author(s):  
Yiji Lu ◽  
Anthony Paul Roskilly ◽  
Long Jiang ◽  
Longfei Chen ◽  
Xiaoli Yu

2021 ◽  
Vol 313 ◽  
pp. 06001
Author(s):  
Siddharth Ramachandran ◽  
Naveen Kumar ◽  
Venkata Timmaraju Mallina

Despite the higher efficiency advantage, the cost reduction of PV technology has been more successful compared to the dish Stirling engine (DSE) due to the large market volume and sturdy competition. Irrespective of the types of source, there exists a potential of waste heat recovery from Stirling engines operating at higher temperature regime. Accordingly, to make DSE commercially viable and efficient, innovative ways such as hybridization (combing a bottoming cycle), Co-generation, Tri-generation etc. need to be explored. In this paper, the techno-economic feasibility of hybridization of a typical solar DSE with a bottoming organic Rankine cycle (ORC) via. a heat recovery vapour generator (HRVG) is explored. The overall energetic and exergetic efficiency of the DSE has been improved by 5.79% and 5.64% while recovering the waste heat through a bottoming ORC. The design and effective incorporation of the HRVG with cooler side of the Stirling engine is identified to be crucial for the overall exergetic performance of solar Stirling-ORC. Further, the economic feasibility of a solar String-ORC combination is evaluated in terms of levelized cost of electricity (LCOE) and payback period. Both LCOE and payback period are found to be in comparable range with the PV technology.


2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Sebastian Araya ◽  
Aaron P. Wemhoff ◽  
Gerard F. Jones ◽  
Amy S. Fleischer

Abstract The ongoing growth in data center rack power density leads to an increased capability for waste heat recovery. Recent studies revealed the organic Rankine cycle (ORC) as a viable means for data center waste heat recovery since the ORC uses waste heat to generate on-site, low-cost electricity, which can produce economic benefits by reducing the overall data center power consumption. This paper describes the first experimental and theoretical study of a lab-scale ORC designed for ultralow grade (40–85 °C) waste heat conditions typical of a data center server rack, and it outlines the implementation of a similar ORC system for a data center. The experimental results show thermal efficiencies ranging from 1.9% at 43 °C to 4.6% at 81 °C. The largest contributors to ORC exergy destruction are the evaporator and condenser due to large fluid temperature differences in the heat exchangers. The average isentropic efficiency of the expander is 70%. A second-law analysis estimates a reduction of 4–8% in data center power requirements when ORC power is fed back into the servers at a waste heat temperature of 90 °C. The data from the lab-scale experiment, when complemented by the thermodynamic model, provide the necessary first step toward advancing this type of waste heat recovery for data centers (DCs).


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