Energy and Exergy Analysis of Different Exhaust Waste Heat Recovery Systems for Natural Gas Engine Based on ORC

Waste heat recovery (WHR) from exhaust gases in natural gas engines improves the overall conversion efficiency. The organic Rankine cycle (ORC) has emerged as a promising technology to convert medium and low-grade waste heat into mechanical power and electricity. This paper presents the energy and exergy analyses of three ORC–WHR configurations that use a coupling thermal oil circuit. A simple ORC (SORC), an ORC with a recuperator (RORC), and an ORC with double-pressure (DORC) configuration are considered; cyclohexane, toluene, and acetone are simulated as ORC working fluids. Energy and exergy thermodynamic balances are employed to evaluate each configuration performance, while the available exhaust thermal energy variation under different engine loads is determined through an experimentally validated mathematical model. In addition, the effect of evaporating pressure on the net power output, thermal efficiency increase, specific fuel consumption, overall energy conversion efficiency, and exergy destruction is also investigated. The comparative analysis of natural gas engine performance indicators integrated with ORC configurations present evidence that RORC with toluene improves the operational performance by achieving a net power output of 146.25 kW, an overall conversion efficiency of 11.58%, an ORC thermal efficiency of 28.4%, and a specific fuel consumption reduction of 7.67% at a 1482 rpm engine speed, a 120.2 L/min natural gas flow, 1.784 lambda, and 1758.77 kW of mechanical engine powe

Analysis of a direct vapor generation system using cascade steam-organic Rankine cycle and two-tank oil storage

A direct vapor generation solar power system using cascade steam-organic Rankine cycle and two-stage oil tanks is proposed. It offers a significantly enlarged storage capacity due to the unique discharge operation mode. Synthetic oil Therminol® VP-1 is used as the heat carrier and storage medium. Compared with the direct steam generation system, the steam turbine inlet temperature is elevated from 270 °C to 311 °C. Thermodynamic analysis indicates that the optimal equivalent heat-to-power conversion efficiency (ηeq,opt) is 27.91% when benzene is used as the bottom fluid and the mass of oil is 1000 tonnes. ηeq,opt is raised by 7.72–11.60% for the selected four organic fluids as compared with the direct steam generation type. The temperature drop of oil during discharge can reach about 280 °C. Economic studies demonstrate that the proposed system is more cost-effective. Its equivalent payback period is less than 5 years for a 10 MW system with 2000 tonnes of oil. Further investigation shows that it is also more advantageous than a conventional thermal oil-based indirect solar power system due to the cost reduction in heat storage

Energy, exergy and economic evaluation comparison of small-scale single and dual pressure organic Rankine cycles integrated with low-grade heat sources

Low-grade heat sources such as solar thermal, geothermal, exhaust gases and industrial waste heat are suitable alternatives for power generation which can be exploited by means of small-scale Organic Rankine Cycle (ORC). This paper combines thermodynamic optimization and economic analysis to assess the performance of single and dual pressure ORC operating with different organic fluids and targeting small-scale applications. Maximum power output is lower than 45 KW while the temperature of the heat source varies in the range 100-200 °C. The studied working fluids, namely R1234yf, R1234ze(E) and R1234ze(Z), are selected based on environmental, safety and thermal performance criteria. Levelized Cost of Electricity (LCOE) and Specific Investment Cost (SIC) for two operation conditions are presented: maximum power output and maximum thermal efficiency. Results showed that R1234ze(Z) achieves the highest net power output (up to 44 kW) when net power output is optimized. Regenerative ORC achieves the highest performance when thermal efficiency is optimized (up to 18%). Simple ORC is the most cost-effective among the studied cycle configurations, requiring a selling price of energy of 0.3 USD/kWh to obtain a payback period of 8 years. According to SIC results, the working fluid R1234ze(Z) exhibits great potential for simple ORC when compared to conventional R245fa

Solar powered desalination – Technology, energy and future outlook

Growing water demands have led to rapidly increasing desalination installation capacity worldwide. In an attempt to lower carbon footprint resulting from high-energy consuming desalination processes, attention has shifted to using renewable energy sources to power desalination. With solar irradiation ample in regions that heavily rely on desalination, solar powered desalination provides a sustainable solution to meeting water needs. The compatibility of each desalination process with the solar technology is driven by whether the kind of energy needed is thermal or electrical, as well as its availability. With rapid advances in solar energy technologies – both photovoltaic and solar thermal, there has also been growing interest in coupling solar energy with desalination, with a focus on improving energy efficiency. In this review, the most recent developments in photovoltaic powered reverse osmosis (PV-RO), solar thermal powered reverse osmosis (ST-RO) are discussed with respect to membrane materials, process configuration, energy recovery devices and energy storage. In addition, advances in new materials for solar powered membrane distillation (MD) and solar stills in the past two years have also been reviewed. Future outlook considers the use of hybrid renewable energy systems as well as solar powered forward osmosis and dewvaporation. Solar powered desalination systems have been analysed with emphasis on technological and energy consumption aspects

Review on Solar Thermal Electricity in Libya

Libya is facing an increasing deficit in electrical energy supply which needs great efforts to find new and renewable alternative sources of power. Solar thermal electricity is one of the most promising and emerging renewable energy technologies to substitute the conventional fossil fuel systems. A review of the research literature of solar thermal electricity in Libya is presented in this article. The state of the art of these technologies including design, operation principles and global market is demonstrated. Detailed reviews of research activities that have been conducted by Libyan researchers or institutions are presented. It has been found that Libya as a country needs a strategic plan and more research efforts in order to adopt these new technologies and put them in production mode

Study of India's Rural Development through Renewable Energy Sources

The rural sector, which is home to the majority of the country's people, must be strengthened if the country is to progress. Infrastructure, village electricity, mechanisation, and other methods should all be employed to make development. Villages in several states face a challenge with centralised generation and distribution systems since grid access is either impossible or too expensive. Power generating, cooking, irrigation, and water heating in rural areas can all benefit from renewable energy sources found in nature. The Indian government has come up with fresh plans and financial assistance for the implementation of such projects at the national and state levels. There are various technologies that can be used to improve the quality of life in rural areas

Solar ORC plant in residential building

U ovom radu dimenzionirano je postrojenje s organskim Rankineovim ciklusom i pločastim solarnim kolektorom kao izvorom topline za stambeni objekt površine 800 m2. Opisane su općenite karakteristike ovog procesa i veličine korištene za izračun. Izveden je pojednostavljeni matematički model komponenti postrojenja te pomoću programa MATLAB simuliran je kontinuirani dnevni pogon sustava u zimskom, prijelaznom i ljetnom režimu na području grada Splita. Izračunata je dnevna proizvodnja električne energije i prikazana na dijagramu. U zaključku se daje usporedba proizvedene energije s pretpostavljenom potrebnom. Prodiskutirana su alternativna rješenja za nedostatke postrojenja.The thesis deals with designing an organic Rankine cycle plant with plate solar collector as heat source in residential building with area of 800 m2. General characteristics of this cycle and used variables are described. A simplified mathematical model of plant components is presented and MATLAB software is used to simulate continuous daily performance in winter, transitional and summer regime for the city of Split. Daily power production is calculated and presented in a chart. A comparison of produced and needed power is given in conclusion, with the discussion on alternative solutions for plant disadvantages

Solarno ORC postrojenje u stambenom objektu

U ovom radu dimenzionirano je postrojenje s organskim Rankineovim ciklusom i pločastim solarnim kolektorom kao izvorom topline za stambeni objekt površine 800 m2. Opisane su općenite karakteristike ovog procesa i veličine korištene za izračun. Izveden je pojednostavljeni matematički model komponenti postrojenja te pomoću programa MATLAB simuliran je kontinuirani dnevni pogon sustava u zimskom, prijelaznom i ljetnom režimu na području grada Splita. Izračunata je dnevna proizvodnja električne energije i prikazana na dijagramu. U zaključku se daje usporedba proizvedene energije s pretpostavljenom potrebnom. Prodiskutirana su alternativna rješenja za nedostatke postrojenja