Thermal Analysis of Heat Recovery Unit to Recover Exhaust Energy for Using in Organic Rankine Cycle

Mamat, Aman Mohd Ihsan; Mohamed, Wan Ahmad Najmi bin Wan

doi:10.4028/www.scientific.net/amm.393.781

Cited by 3 publications

(4 citation statements)

References 7 publications

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“…As mentioned earlier, the present study deals with steady state heat transfer analysis of WHE that could provide significant information for the development of a 3 kW-ORC waste heat recovery system from the exhaust gas of ICE using ammonia as an operating fluid. Since the efficiency of ORC-NH 3 is estimated to be 25% [24], the exhaust gas from ICE is needed to produce heat transfer rates of 12 kW through counterflow WHE. During analysis, parameters such as different exhaust gas temperature, mass flow rate, defined temperature of operating fluid, and WHE geometry configurations were taken into account and presented here.…”

Section: Resultsmentioning

confidence: 99%

“…The ICE exhaust gas temperature is between 200°C and 900°C, depending on engine load. Ammonia (NH 3 ) is chosen as the organic operating fluid (OOF) in the ORC due to high effectiveness, with a maximum value of 0.25, compared to hydrocarbons like propane (C 3 H 8 ) in which the maximum value of effectiveness is ɛ = 0.16 [24]. In Figure 1, the exhaust gas as a heat source is shown to enter the WHE and the heat is transferred into the OOF.…”

Section: Organic Rankine Cyclementioning

confidence: 99%

“…Since a waste heat exchanger (WHE) is one of the key components in waste heat recovery, the present study performs heat transfer analysis of a simple counterflow WHE that could provide significant information for the development of 3 kW-ORC waste heat recovery system from the exhaust gas of ICE using ammonia as an organic operating fluid. Since the ORC-NH 3 efficiency is estimated to be 25% [24], the exhaust gas from ICE needs to produce heat transfer rates of 12 kW through counterflow type of WHE.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Heat Transfer Analysis of Waste Heat Exchanger for Exhaust Gas Energy Recovery

2015

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Waste heat is heat that is usually thrown into the environment even though it could still be reused for some useful and economic purpose. For example, any exhaust gas stream with a temperature of above 80°C has the potential for significant waste heat recovery. Therefore, an attempt to reuse the exhaust waste energy to transfer the energy to any energy cycle is a worthwhile effort. In the present study, the waste energy from the exhaust gas of an internal combustion engine is recovered by converting it to ammonia (NH 3) as an organic operating fluid in the Organic Rankine Cycle (ORC), which aims to produce 3 kW turbine power. To achieve a specific amount of energy, a key component in waste heat recovery is the heat exchanger. In the present study, a steady-state numerical analysis of heat transfer is conducted for various dimensional configurations of the waste heat exchanger using ammonia. The findings showed that the exhaust gas mass flow rate only has a very minimal effect on the length of the pipe when the exhaust temperature exceeds 400°C.

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Section: Resultsmentioning

confidence: 99%

Section: Organic Rankine Cyclementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Heat Transfer Analysis of Waste Heat Exchanger for Exhaust Gas Energy Recovery

2015

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“…In a well-designed ORC, the net backpressure can actually be lower due to excessive cooling of the exhaust gas in the evaporator [85]. Moreover, the combination of the ORC system and the automotive engine increases the thermal efficiencies of the engine without increasing the exhaust back-pressure [86,87]. Another main drawback of turbo-compounding technology is the increase in pumping losses due the existence of the extra turbine.…”

Section: Comparison Between Orc System and Other Technologies (Thermomentioning

confidence: 99%

Expander Technologies for Automotive Engine Organic Rankine Cycle Applications

Alshammari

Karvountzis-Kontakiotis

Pesyridis

et al. 2018

Energies

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The strive towards ever increasing automotive engine efficiencies for both diesel and gasoline engines has in recent years been forced by ever-stringent emissions regulations, as well as the introduction of fuel consumption regulations. The untapped availability of waste heat in the internal combustion engine (ICE) exhaust and coolant systems has become a very attractive focus of research attention by industry and academia alike. Even state of the art diesel engines operating at their optimum lose approximately 50% of their fuel energy in the form of heat. As a result, waste heat recovery (WHR) systems have gained popularity as they can deliver a reduction in fuel consumption and associated CO2 emissions. Of these, the Organic Rankine Cycle (ORC) is a well matured waste heat recovery technology that can be applied in vehicle powertrains, mainly due to the low additional exhaust backpressure on the engine and the potential opportunity to utilize various engine waste heat sources. ORCs have attracted high interest again recently but without commercial exploitation as of today due to the significant on-cost they represent to the engine and vehicle. In ORCs, expansion machines are the interface where useable power production takes place; therefore, selection of the expander technology is directly related to the thermal efficiency of the system. Moreover, the cost of the expander-generator units accounts for the largest proportion of the total cost. Therefore, selection of the most appropriate expander is of great importance at the early stage of any automotive powertrain project. This study aims to review the relevant research studies for expansion machines in ORC-ICE applications, analyzing the effects of specific speed on expander selection, exploring the operational characteristics of each expander to further assist in the selection of the most appropriate expander, and comparing the costs of various expanders based on publically available data and correlations.

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Thermophysical Properties Analysis for Ammonia-Water Mixture of an Organic Rankine Cycle

et al. 2015

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In an Organic Rankine Cycle (ORC), the thermofluid properties of the organic fluid are key parameters to achieve an optimum energy recovery. Non-azeotrapic fluid, such as ammonia-water mixture is suitable for applications in low grade heat source because of the thermodynamic characteristics of this fluid. This paper reports experimental data of thermal conductivity and dynamic viscosity of ammonia-water mixtures that will be used for ORC application. Five ratios of ammonia to water concentration were tested which are; (1) 25:75, (2) 20:80, (3) 15:85, (4) 10:90 and (5) 5:95. These five mixtures are characterized at a temperature range from 25ºC to 40ºC. The result shows that the thermal conductivity increases as the concentration of the ammonia reduces. The thermal conductivity also increases as the mixture temperature increases. The ammonia-water mixture at the ratio of 5:95 gives the highest thermal conductivity at 40ºC which is 30% better than the other concentrations at similar temperature. The dynamic viscosity, and heat capacity, of these mixtures shows a linear relationship to ammonia molar concentration.

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Thermal Analysis of Heat Recovery Unit to Recover Exhaust Energy for Using in Organic Rankine Cycle

Cited by 3 publications

References 7 publications

Numerical Heat Transfer Analysis of Waste Heat Exchanger for Exhaust Gas Energy Recovery

Numerical Heat Transfer Analysis of Waste Heat Exchanger for Exhaust Gas Energy Recovery

Expander Technologies for Automotive Engine Organic Rankine Cycle Applications

Thermophysical Properties Analysis for Ammonia-Water Mixture of an Organic Rankine Cycle

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