scholarly journals Thermal Analysis of Waste Heat Recovery Systems Using CFD

2021 ◽  
Vol 4 (3) ◽  
pp. 1-5
Author(s):  
C. Ganesh ◽  
M. Shivshankar ◽  
P. Harisha
Keyword(s):  
Heat Recovery ◽  
Energy Savings ◽  
Waste Heat ◽  
Emission Control ◽  
Dew Point ◽  
Feed Water ◽  
Gas Generation ◽  
Heating Unit ◽  
Control Equipment ◽  
Intermediate Unit

The project statement is to optimize the heat transfer in a compact heat recovery unit (Heat Recovery and Emission Control Equipment - HREC) using CFD with application in day to day life. In general, the outgoing exhaust gasses are released to atmosphere at over temperature of the dew point of water vapor in waste gases. Recovering a portion of the waste heat enhances the efficiency of the equipment and as well reduce the emissions providing energy savings and green environment. In this study, the potential of recovering waste heat emitted by any heat generation units in common day to day life and in industry is considered. The Heat Recovery and Emission Control Equipment (HREC) acts an intermediate unit at the exit of hot gas generation unit & feed water heating unit. As a result of the calculation, it was determined that recovery of the waste heat can be employed at many applications as like as a combustion air preheater by means of a recuperator.  

Efficient Heat Transfer From Non-Condensable Gas in the Process of Moist Exhaust Heat Recovery

2013 ◽  
Author(s):  
Helen Skop ◽  
Valeriy G. Oleynikov-White
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Energy Savings ◽  
Waste Heat ◽  
Heat Transfer Surface ◽  
Operating Conditions ◽  
Dew Point ◽  
Exhaust Heat ◽  
High Efficient ◽  
Low Efficiency

Most of the industrial waste heat is in the low temperature range. In the last few years, government agencies and equipment developers have paid attention to the advantages of heat recovery from moist industrial exhausts by cooling them to below the corresponding dew point temperature level. In case of non-aggressive and highly moisturized exhaust gas the recovery of vapor latent heat through efficient condensation can provide with significant energy savings. Indirect cooling condensers are it’s the simplest solution for such heat recovery. However, low efficiency of those condensers makes the heat recovery economically not feasible. To develop a high efficient heat and mass exchanger it is necessary to investigate the combined transfer mechanisms from exhaust vapor and non-condensable portion of the exhaust to the heat transfer surface through the condensing water vapor. This paper describes main approaches to the description of this heat and mass transfer process, operating conditions for efficient gas cooling along with interaction between non-condensable gas and condensing vapor as well as considerations of influence of heat transfer surface on efficient condensation.

Feasibility Study of a Supercritical Cycle as a Waste Heat Recovery System

2013 ◽  
Author(s):  
Antonio Agresta ◽  
Antonella Ingenito ◽  
Roberto Andriani ◽  
Fausto Gamma
Keyword(s):  
Power Systems ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Energy Savings ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Organic Fluids

Following the increasing interest of aero-naval industry to design and build systems that might provide fuel and energy savings, this study wants to point out the possibility to produce an increase in the power output from the prime mover propulsion systems of aircrafts. The complexity of using steam heat recovery systems, as well as the lower expected cycle efficiencies, temperature limitations, toxicity, material compatibilities, and/or costs of organic fluids in Rankine cycle power systems, precludes their consideration as a solution to power improvement for this application in turboprop engines. The power improvement system must also comply with the space constraints inherent with onboard power plants, as well as the interest to be economical with respect to the cost of the power recovery system compared to the fuel that can be saved per flight exercise. A waste heat recovery application of the CO2 supercritical cycle will culminate in the sizing of the major components.

scholarly journals Experimental evaluation of two consecutive air-gap membrane distillation modules with heat recovery

2020 ◽  
Vol 20 (5) ◽  
pp. 1678-1691 ◽  
Author(s):  
Mostafa Abd El-Rady Abu-Zeid ◽  
Gamal ElMasry
Keyword(s):  
Water Temperature ◽  
Flow Rate ◽  
Heat Recovery ◽  
Waste Heat ◽  
Water Flow Rate ◽  
Membrane Distillation ◽  
Air Gap ◽  
Feed Water ◽  
System Productivity ◽  
Air Gap Membrane Distillation

Abstract Two rectangular modules with a total interior membrane surface area of 13.53 m2 were consecutively combined to evaluate the use of heat recovery in an air-gap membrane distillation (AGMD) system. Several operating inlet parameters including feed water temperature, mass water flow rate and salinity were investigated. The experimental results revealed that the performance of the system was improved by virtue of efficient heat recovery resulting from combining two AGMD membrane modules in series. Under optimal inlet operating parameters of cooling water temperature of 20 °C, salinity of 0.05% and flow rate of 3 l/min, the system productivity (Pp) increased up to 192.9%, 179.3%, 176.5% and 179.2%, and the thermal efficiency (ηth) by 261.5%, 232.6%, 239.4% and 227.3% at feed water temperatures of 45 °C, 55 °C, 65 °C and 75 °C, respectively. Concurrently, the specific waste heat input (Ew.h.i) decreased by 6.7%, 4.7%, 5.6% and 2.7% due to the efficient heat recovery. The results confirmed that heat recovery is an important factor affecting the AGMD system that could be improved by designing one of the two AGMD modules with polytetrafluoroethylene (PTFE) hollow fibers with a flow length shorter than the other one having a salt rejection rate of 99%.

Heat and Mass Transfer in Double-Filmwise Heat Exchanger for Industrial Food Processing Applications

2011 ◽  
Author(s):  
Helen Skop ◽  
James Pezzuto ◽  
Valeriy G. Oleynikov-White ◽  
John F. Cavallo ◽  
Robert Fesjian
Keyword(s):  
Water Vapor ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cost Effective ◽  
Dew Point ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Gas Cooling ◽  
Stack Gas

The baking industry is considered as one of the major energy consuming food industries in North America. More than 40% of bakery fuel consumption is used to evaporate water in the processes [1]. In addition to the baking process’ vapor the oven stack gas contains water vapor from combustion products. Overall the content of water vapor in the typical oven stack gas is about 20% by volume. Most bakeries waste this vapor and its latent heat. Bakeries’ ovens have wide diversity in power and design. Off-the-shelve heat exchangers are not considered as cost effective equipment for stack gas cooling below gas’ dew point temperature. At typical oven stack gas composition water vapor condensation begins to condense at about 72° C. Not using the latent heat of stack water vapor and the heat from gas cooling from dew point temperature to ambient temperature results in low effectiveness of waste heat recovery. Mainly the effect from the recovery of stack gas cooling prior to condensation is considered as non cost effective and waste heat recovery is neglected.

scholarly journals Improving the efficiency of heat recovery circuits of cogeneration plants with combustion of water-fuel emulsions

2020 ◽  
pp. 154-154 ◽  
Author(s):  
Victoria Kornienko ◽  
Mykola Radchenko ◽  
Roman Radchenko ◽  
Dmytro Konovalov ◽  
Andrii Andreev ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Power Plant ◽  
Heat Recovery ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Dew Point ◽  
Exhaust Gas ◽  
Direct Flow ◽  
Exhaust Heat ◽  
Heating Surfaces

When using modern highly efficient internal combustion engines with lowered potential of exhaust heat the heat recovery systems receive increasing attention. The efficiency of combustion exhaust heat recovery at the low potential level can be enhanced by deep cooling the combustion products below a dew point temperature, which is practically the only possibility for reducing the temperature of boiler exhaust gas, while ensuring the reliability, environmental friendliness and economy of power plant. The aim of research is to investigate the influence of multiplicity of circulation and temperature difference at the exit of exhaust gas boiler heating surfaces, which values are varying as 20, 15, 10?C, on exhaust gas boiler characteristics. The calculations were performed to compare the constructive and thermal characteristics of the various waste heat recovery circuits and exhaust gas boiler of ship power plant. Their results showed that due to application of condensing heating surfaces in exhaust gas boiler the total heat capacity and steam capacity of exhaust gas boiler increases. The increase of exhaust gas boiler heat capacity is proportional to the growth of its overall dimensions. A direct-flow design of the boiler provides a significant increase in heat efficiency and decrease in dimensions. In addition, a direct-flow boiler circuit does not need steam separator, circulation pump, the capital cost of which is about half (or even more) of heating surface cost.

scholarly journals Review on Energy Efficiency Progresses, Technologies and Strategies in the Ceramic Sector Focusing on Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6096
Author(s):  
Miguel Castro Oliveira ◽  
Muriel Iten ◽  
Pedro L. Cruz ◽  
Helena Monteiro
Keyword(s):  
Energy Efficiency ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Manufacturing Industry ◽  
Energy Savings ◽  
High Efficiency ◽  
Waste Heat ◽  
Hot Air ◽  
Plant Level

Thermal processes represent a considerable part of the total energy consumption in manufacturing industry, in sectors such as steel, aluminium, cement, ceramic and glass, among others. It can even be the predominant type of energy consumption in some sectors. High thermal energy processes are mostly associated to high thermal losses, (commonly denominated as waste heat), reinforcing the need for waste heat recovery (WHR) strategies. WHR has therefore been identified as a relevant solution to increase energy efficiency in industrial thermal applications, namely in energy intensive consumers. The ceramic sector is a clear example within the manufacturing industry mainly due to the fuel consumption required for the following processes: firing, drying and spray drying. This paper reviews studies on energy efficiency improvement measures including WHR practices applied to the ceramic sector. This focuses on technologies and strategies which have significant potential to promote energy savings and carbon emissions reduction. The measures have been grouped into three main categories: (i) equipment level; (ii) plant level; and (iii) outer plant level. Some examples include: (i) high efficiency burners; (ii) hot air recycling from kilns to other processes and installation of heat exchangers; and (iii) installation of gas turbine for combined heat and power (CHP). It is observed that energy efficiency solutions allow savings up to 50–60% in the case of high efficiency burners; 15% energy savings for hot air recycling solutions and 30% in the when gas turbines are considered for CHP. Limitations to the implementation of some measures have been identified such as the high investment costs associated, for instance, with certain heat exchangers as well as the corrosive nature of certain available exhaust heat.

A Heat Recovery Study: Application of Intercooler as a Feed-Water Heater of Heat Recovery Steam Generator

2010 ◽  
Author(s):  
P. Shukla ◽  
M. Izadi ◽  
P. Marzocca ◽  
D. K. Aidun
Keyword(s):  
Steam Generator ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Waste Heat ◽  
Feed Water ◽  
Heat Recovery Steam Generator ◽  
Steam Generation ◽  
Water Heater ◽  
Theoretical Support ◽  
Recovery Study

This paper evaluates the possibility of combining an intercooled gas turbine power cycle with a steam turbine cycle and the application of the intercooler as a feed-water heater for the heat recovery steam generator. In advance gas turbines the intercooler is used to improve the overall efficiency of the simple cycle but a noticeable amount of heat is wasted to the atmosphere. However, this energy can be recovered by using the proposed method in the current study. Accordingly, a thermodynamic study is done to investigate the improvement in efficiency achieved by feed-water heating. First the effect of intercooler parameters on the outlet condition of the water is studied. The bottoming cycle is then studied in details for the effect of feed-water temperature. An estimate of the energy saving by using the proposed method will be reported. The results show that less heat input will be required for the same amount of steam generation. The current study provides a theoretical support for waste heat recovery from the intercooler.

A Novel Flue Gas Heat Recovery System Integrated With Air Preheating in a Utility Boiler

2013 ◽  
Author(s):  
Cheng Xu ◽  
Gang Xu ◽  
Luyao Zhou ◽  
Yongping Yang ◽  
Yuanyuan Li ◽  
...  
Keyword(s):  
Flue Gas ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Energy Savings ◽  
Waste Heat ◽  
The Novel ◽  
Air Preheater ◽  
Recovery System ◽  
Condensed Water

Exhaust gas temperature in coal-fired power plants can reach approximately 120 °C to 140 °C, with the thermal energy accounting for approximately 3% to 8% of the total input energy. Therefore, the heat recovery of exhaust flue gas can improve the thermal efficiency of coal-fired power plants. Currently, the waste heat of flue gas can be recovered by installing an extra heat exchanger, also called low-temperature economizer (LTE), at the end of the boiler flue to heat a part of the condensed water. Extra work can then be obtained by saving the extracted steam and using it to heat the condensed water. However, the temperature of exhaust flue gas is only about 130 °C, which causes the flue gas to heat only the condensed water in the #7 and #8 regenerative heaters. Thus, the energy savings are inconspicuous. This paper proposes a novel flue gas heat recovery system to dramatically increase the temperature of flue gas in the LTE by comprehensive optimization of the air preheater and the LTE. A low-temperature (LT) air preheater can be installed after the LTE in the novel system so that the flue gas can be divided into two parts to heat the air. Simultaneously, the LTE can be installed between the two air preheaters, causing the temperature of flue gas in the LTE to reach above 170 °C. Hence, the temperature of condensed water in the LTE can be increased significantly. In addition, the LTE can replace the high-pressure extracted steam from the turbine, resulting in better energy savings. We also conduct case studies based on a typical 1,000 MW supercritical power generation unit in China. The results indicate better performance of the novel system, with a decrease in exergy loss and improvement in heat transfer characteristics. The reduction in standard coal equivalent of the novel system can reach 3.31g/kWh, nearly 2.4 times that of the system that uses conventional waste heat recovery. Our achievements provide a promising waste heat recovery methods of the utility boiler flue gas.

scholarly journals Waste Heat Recovery Technologies Revisited with Emphasis on New Solutions, including Heat Pipes, and Case Studies

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 384
Author(s):  
Paul Christodoulides ◽  
Rafaela Agathokleous ◽  
Lazaros Aresti ◽  
Soteris A. Kalogirou ◽  
Savvas A. Tassou ◽  
...  
Keyword(s):  
Case Studies ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Energy Savings ◽  
New Technologies ◽  
Waste Heat ◽  
Cost Savings ◽  
Energy Performance ◽  
The European Union ◽  
Target Energy

Industrial processes are characterized by energy losses, such as heat streams rejected to the environment in the form of exhaust gases or effluents occurring at different temperature levels. Hence, waste heat recovery (WHR) has been a challenge for industries, as it can lead to energy savings, higher energy efficiency, and sustainability. As a consequence, WHR methods and technologies have been used extensively in the European Union (EU) (and worldwide for that matter). The current paper revisits and reviews conventional WHR technologies, their use in all types of industry, and their limitations. Special attention is given to alternative “new” technologies, which are discussed for parameters such as projected energy and cost savings. Finally, an extended review of case studies regarding applications of WHR technologies is presented. The information presented here can also be used to determine target energy performance, as well as capital and installation costs, for increasing the attractiveness of WHR technologies, leading to the widespread adoption by industry.

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