Exergy Analysis of Natural Gas ICE-Based CHP System

2009 ◽  
Author(s):  
Xiling Zhao ◽  
Lin Fu ◽  
Shigang Zhang ◽  
Jianzhang Zhu ◽  
Baomin Huang ◽  
...  
Keyword(s):  
Natural Gas ◽  
Heat Recovery ◽  
Waste Heat ◽  
Operation Mode ◽  
Mode I ◽  
Mode Ii ◽  
Exhaust Gas ◽  
Liquid Desiccant ◽  
Water Flows ◽  
Recovery Unit

A challenge for CHP (Combined heating and power) system is the efficient integration of distributed generation (DG) equipment with thermally-activated (TA) technologies. Tsinghua University focuses on laboratory and demonstration research to study the critical issues of CHP systems, advance the technology and accelerate its application. The Research performed at the Building Energy Research Center (BERC) Laboratory focuses on assessing the operational performance and efficiency of the integration of current DG and TA technologies. The test system is composed of a 70-kW natural gas-fired internal combustion engine (ICE) with various heat recovery units, such as a flue gas-to-water heat recovery unit (FWRU), a jacket water heat recovery unit (JRU), liquid desiccant dehumidification systems (LDS), an exhaust-gas-driven double-effect absorption heat pump (EDAHP), and a condensation heat recovery unit (CRU)). In the winter, the exhaust gas from the ICE is used in the FWRU (operation mode I) or used to drive the EDAHP directly, and the exhaust gas from the EDAHP is used in the CRU (operation mode II). The water flows from the CRU can be directed to the evaporator side of the EDAHP as the lower-grade heat source. The water flows from the condensation side of the EDAHP, in conjunction with the jacket water flows from the JRU, is used for heating. In summer, the exhaust gas from the ICE is used to drive the EDAHP for cooling directly, and the waste heat of the jacket water is used to drive the liquid desiccant dehumidification systems, to realize the separate control of heat and humidity. In this paper, the exergy and energy analysis has been done on operation mode I and II according to the actual testing results, and it is show that the exergy efficiency of operation mode II is improved by 1.5% than operation mode I, and the energy efficiency of operation mode II is improved by 11% than operation mode I. The only way to improve the whole CHP is to maximize the use of the heat recovered by the ICE and to utilize the remaining heat of exhaust gas in other waste-heat driven equipments capable of using low grade waste heat like the CRU.

Energetic Based Organic Fluid Selection for a Solid Oxide Fuel Cell-Organic Rankine Cycle Combined System

2012 ◽  
Vol 622-623 ◽  
pp. 1162-1167
Author(s):  
Han Fei Tuo
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Heat Recovery ◽  
Waste Heat ◽  
Solid Oxide ◽  
Exhaust Gas ◽  
Oxide Fuel ◽  
Gas Temperature ◽  
Selection For ◽  
Exhaust Gas Temperature

In this study, energetic based fluid selection for a solid oxide fuel cell-organic rankine combined power system is investigated. 9 dry organic fluids with varied critical temperatures are chosen and their corresponding ORC cycle performances are evaluated at different turbine inlet temperatures and exhaust gas temperature (waste heat source) from the upper cycle. It is found that actual ORC cycle efficiency for each fluid strongly depends on the waste heat recovery performance of the heat recovery vapor generator. Exhaust gas temperature determines the optimal fluid which yields the highest efficiency.

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

2019 ◽  
Author(s):  
Guillermo Valencia ◽  
Armando Fontalvo ◽  
Yulineth Cardenas ◽  
Jorge Duarte ◽  
Cesar Isaza
Keyword(s):  
Natural Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Exergy Analysis ◽  
Waste Heat ◽  
Natural Gas Engine ◽  
Exhaust Waste Heat ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Net Power Output

One way to increase overall natural gas engine efficiency is to transform exhaust waste heat into useful energy by means of a bottoming cycle. Organic Rankine cycle (ORC) is a promising technology to convert medium and low grade waste heat into mechanical power and electricity. This paper presents an energy and exergy analysis of three ORC-Waste heat recovery configurations by using an intermediate thermal oil circuit: Simple ORC (SORC), ORC with Recuperator (RORC) and ORC with Double Pressure (DORC), and Cyclohexane, Toluene and Acetone have been proposed as working fluids. An energy and exergy thermodynamic model is proposed to evaluate each configuration performance, while available exhaust thermal energy variation under different engine loads was determined through an experimentally validated mathematical model. Additionally, the effect of evaportating pressure on net power output , absolute thermal efficiency increase, absolute specific fuel consumption decrease, overall energy conversion efficiency, and component exergy destruction is also investigated. Results evidence an improvement in operational performance for heat recovery through RORC with Toluene at an evaporation pressure of 3.4 MPa, achieving 146.25 kW of net power output, 11.58% of overall conversion efficiency, 28.4% of ORC thermal efficiency, and an 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 mechanical engine power.

scholarly journals Comparative analysis of working fluids for efficient waste heat recovery

2021 ◽  
Vol 2057 (1) ◽  
pp. 012102
Author(s):  
D Ye Lola ◽  
A Yu Chirkov ◽  
Yu A Borisov
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Exhaust Gas ◽  
Water Cooling ◽  
Working Fluids ◽  
Gas Recovery ◽  
Recovery System

Abstract The paper analyzes the implementation of plants with an organic Rankine cycle (ORC) on the example of the circuit of the regenerative gas turbine unit and exhaust gas recovery system of the compressor system of the gas-compressor unit. The theoretically achievable values of power generated by the ORC-installations are determined. A criterion is presented for comparing the working fluids according to the efficiency of use in ORC-installations. To evaluate the overall characteristics of the system, the parameters of heat exchangers for air and water cooling were determined. As a result, it is concluded that the use of ORC-installations allows to utilize up to 23% of the heat of exhaust gases (convert into useful work).

Residential Experience with Proton Exchange Membrane Fuel Cell Systems for Combined Heat and Power

2005 ◽  
Vol 2 (4) ◽  
pp. 263-267 ◽  
Author(s):  
Darrell D. Massie ◽  
Daisie D. Boettner ◽  
Cheryl A. Massie
Keyword(s):  
Fuel Cell ◽  
Natural Gas ◽  
Heat Recovery ◽  
Proton Exchange Membrane ◽  
Waste Heat ◽  
Cell System ◽  
Proton Exchange ◽  
Fuel Cell System ◽  
Cell Systems ◽  
Exchange Membrane

As part of a one-year Department of Defense demonstration project, proton exchange membrane fuel cell systems have been installed at three residences to provide electrical power and waste heat for domestic hot water and space heating. The 5kW capacity fuel cells operate on reformed natural gas. These systems operate at preset levels providing power to the residence and to the utility grid. During grid outages, the residential power source is disconnected from the grid and the fuel cell system operates in standby mode to provide power to critical loads in the residence. This paper describes lessons learned from installation and operation of these fuel cell systems in existing residences. Issues associated with installation of a fuel cell system for combined heat and power focus primarily on fuel cell siting, plumbing external to the fuel cell unit required to support heat recovery, and line connections between the fuel cell unit and the home interior for natural gas, water, electricity, and communications. Operational considerations of the fuel cell system are linked to heat recovery system design and conditions required for adequate flow of natural gas, air, water, and system communications. Based on actual experience with these systems in a residential setting, proper system design, component installation, and sustainment of required flows are essential for the fuel cell system to provide reliable power and waste heat.

Supercharged Expander to Enhance Waste Heat Recovery Through ORC-Based Recovery Unit in Vehicle Applications

2021 ◽  
Author(s):  
Davide Di Battista ◽  
Fabio Fatigati ◽  
Marco DI BARTOLOMEO ◽  
Roberto Cipollone
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Recovery Unit

Recovery and effective utilization of waste heat from the exhaust of internal combustion engines for cooling applications using ANSYS

2021 ◽  
pp. 095440622110568
Author(s):  
Ghulam Abbas Gohar ◽  
Muhammad Zia Ullah Khan ◽  
Hassan Raza ◽  
Arslan Ahmad ◽  
Yasir Raza ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Heat Recovery ◽  
Waste Heat ◽  
Internal Combustion ◽  
Heat Energy ◽  
Exit Velocity ◽  
Inlet Velocity ◽  
Exhaust Gases ◽  
Recovery Unit ◽  
Libr Solution

The exhaust gases from an internal combustion (IC) engine carry away about 75% of the heat energy which means only 25% of heat energy is operated for power production. A recovery unit at the exhaust outlet port can ensure heat exchange between different temperature fluids through conjugate heat transfer phenomena. This study represents heat recovery from exhaust gases that are emitted from IC engines which can be utilized in various applications such as vapor absorption refrigeration systems. In the present work, a new type of perforated fin heat exchanger for waste heat recovery of exhaust gases is designed using SolidWorks, and the flow field design of the heat recovery system is optimized using ANSYS software. Various parameters (velocity, pressure, temperature, and heat conduction) of hot and cold fluid have been analyzed. Inlet velocity of cold fluids including refrigerant (LiBr solution), water, and graphene oxide (GO) nanofluid have been adopted at 0.03 m/s, 0.165 m/s, and 0.3 m/s, respectively. Inlet velocity of hot fluid is taken as 2 m/s, 4 m/s, and 6 m/s, respectively, to develop a test matrix. The results showed that maximum temperature reduction by the exhaust is achieved at 104.8°C using graphene oxide nanofluids with an inlet velocity of 0.3 m/s and exit velocity of 2 m/s in the heat recovery unit. Similarly, temperature reduction by exhaust gases is acquired at 102 °C using water and 96.34 °C by using a refrigerant (LiBr solution) with the same exit velocity (2 m/ s). Furthermore, maximum effectiveness of 0.489 is also obtained for GO nanofluid when compared with water and the refrigerant. On the other hand, the refrigerant has the maximum log mean temperature difference from all fluids with a value of 224.4 followed by water and GO.

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