scholarly journals Energy efficiency of membrane distillation: Simplified analysis, heat recovery, and the use of waste-heat

2020 ◽  
Vol 138 ◽  
pp. 105588 ◽  
Author(s):  
Kofi S.S. Christie ◽  
Thomas Horseman ◽  
Shihong Lin
Keyword(s):  
Energy Efficiency ◽  
Heat Recovery ◽  
Waste Heat ◽  
Membrane Distillation ◽  
Simplified Analysis

scholarly journals Energy and Exergy Analyses of Tube Banks in Waste Heat Recovery Applications

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2094 ◽  
Author(s):  
Mustafa Erguvan ◽  
David MacPhee
Keyword(s):  
Energy Efficiency ◽  
Reynolds Number ◽  
Heat Recovery ◽  
Waste Heat ◽  
Cross Flow ◽  
Exergy Efficiency ◽  
Circular Cylinders ◽  
Published Data ◽  
Energy And Exergy ◽  
Exergy Analyses

In this study, energy and exergy analyses have been investigated numerically for unsteady cross-flow over heated circular cylinders. Numerous simulations were conducted varying the number of inline tubes, inlet velocity, dimensionless pitch ratios and Reynolds number. Heat leakage into the domain is modeled as a source term. Numerical results compare favorably to published data in terms of Nusselt number and pressure drop. It was found that the energy efficiency varies between 72% and 98% for all cases, and viscous dissipation has a very low effect on the energy efficiency for low Reynolds number cases. The exergy efficiency ranges from 40–64%, and the entropy generation due to heat transfer was found to have a significant effect on exergy efficiency. The results suggest that exergy efficiency can be maximized by choosing specific pitch ratios for various Reynolds numbers. The results could be useful in designing more efficient heat recovery systems, especially for low temperature applications.

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%.

scholarly journals Impact of waste heat recovery systems on energy efficiency improvement of a heavy-duty diesel engine

2017 ◽  
Vol 38 (3) ◽  
pp. 63-75 ◽  
Author(s):  
Zheshu Ma ◽  
Hua Chen ◽  
Yong Zhang
Keyword(s):  
Energy Efficiency ◽  
Diesel Engine ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Reduction Factor ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Container Ship ◽  
Large Container

Abstract The increase of ship’s energy utilization efficiency and the reduction of greenhouse gas emissions have been high lightened in recent years and have become an increasingly important subject for ship designers and owners. The International Maritime Organization (IMO) is seeking measures to reduce the CO2 emissions from ships, and their proposed energy efficiency design index (EEDI) and energy efficiency operational indicator (EEOI) aim at ensuring that future vessels will be more efficient. Waste heat recovery can be employed not only to improve energy utilization efficiency but also to reduce greenhouse gas emissions. In this paper, a typical conceptual large container ship employing a low speed marine diesel engine as the main propulsion machinery is introduced and three possible types of waste heat recovery systems are designed. To calculate the EEDI and EEOI of the given large container ship, two software packages are developed. From the viewpoint of operation and maintenance, lowering the ship speed and improving container load rate can greatly reduce EEOI and further reduce total fuel consumption. Although the large container ship itself can reach the IMO requirements of EEDI at the first stage with a reduction factor 10% under the reference line value, the proposed waste heat recovery systems can improve the ship EEDI reduction factor to 20% under the reference line value.

scholarly journals Cuk Converter for Waste Heat Recovery from Automobile Engine using Thermoelectric Generator with Air as Coolant

2020 ◽  
Vol 9 (4) ◽  
pp. 249-252
Keyword(s):  
Energy Efficiency ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Thermoelectric Generator ◽  
Waste Heat ◽  
Combustion Engine ◽  
Electrical Energy ◽  
Internal Combustion ◽  
Heat Energy ◽  
Maximum Power

The growing concern on energy conservation and reduction of carbon footprint has led to a lot of inventions and innovations in terms of energy-efficient technologies in all the energy consuming applications. The automobile sector is a crucial zone where these technologies have a major role to play due to the sheer abundance of the number of automobiles.Many small refinements, alterations and innovations are happening in this field which has led to furthermore energy economic automobiles than before.But even in an advanced internal combustion engine, about two-thirds of fuel consumed by an automobile is discharged into the surroundings as waste heat. The effect of this is the increase in the surrounding air temperature which in turn contributes significantly to global warming. This paper proposes amethod to reduce the emission of heat from automobiles by designing and implementinga waste heat recovery system for internal combustion (IC) engines. The key aim is to reduce the amount of heat released into the environment and to convert it into useful energy. A thermoelectric generator (TEG) assembly is used to directly convert the wasted heat energy from the automobile into electrical energy. This electrical energy is conditioned using a Cukconverter and maximum power point tracking (MPPT) algorithm is embedded in the converter for impedance matching and maximum power transfer from TEG to the converter. The conditioned output is used to charge the battery of the vehicle. This methodologyalso increases the energy efficiency of the vehicle as a higher capacity battery can be employed.The proposed system can work well under varying temperature conditions to give a constant output. It can be implemented in any mechanical/ electrical systems were there is wastage of heat energy like gas pipelines, wearable electronics, space probes, cookstoves, boilers, thermal vision, etc. One of the thrust areas where this technology can be effectively utilized in today’s world is in electric vehicles where the energy efficiency is the most important factor.

scholarly journals Design and Simulation of a Waste Heat Recovery System for a Cement Manufacturing Process

2021 ◽  
Vol 23 (06) ◽  
pp. 1092-1101
Author(s):  
Tharun Sivakumar ◽  
Keyword(s):  
Energy Efficiency ◽  
Manufacturing Process ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Successful Implementation ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Heat Recovery System

As the ever-changing world continues to desperately look for alternative energy sources in the midst of an energy crisis, new technologies to recover power are revealing themselves and being implemented all across the globe. Most power plants are looking for more sustainable sources of energy over the long term. One such technology being adopted now by a lot of enterprises are Energy Recovery Systems. These systems work to retain and reuse energy that would otherwise be lost to the atmosphere after a certain process. They are sustainable and require comparatively lower capital. The objectives of this project revolve around the modelling of a Waste Heat Recovery System (WHRS) for a heat-intensive manufacturing process. The heat, which would otherwise be lost to the atmosphere, is trapped and converted by a heat recovery unit into reusable energy. The main principle on which such a system would operate is The Rankine Cycle, an idealized thermodynamic cycle. Successful implementation of such an energy recovery system would not just boost energy efficiency but also reduce operational costs. The modeling and simulation of the heat recovery system are done on an open-source chemical process flow software known as DWSIM. An analysis of this heat recovery model shows an increase of 19.66% in the energy efficiency of the manufacturing process. Heat recovery systems also have great benefits for the environment, as they reduce the emissions of greenhouse gases by such manufacturing plants and help reduce global warming.

An Innovative Heating Energy System Planning and Design: Case of Yinchuan City

2013 ◽  
Author(s):  
Zhonghai Zheng ◽  
Lin Fu ◽  
Zi Wu ◽  
Xiling Zhao ◽  
Yanting Wu
Keyword(s):  
Energy Efficiency ◽  
Heat Exchange ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Economic Cost ◽  
Heating System ◽  
High Energy ◽  
Large Temperature ◽  
Energy Structure

The current heating system in Yinchuan city, the capital of the Ningxia Autonomous Region in northwest China, is investigated and analyzed. Lacking an integrated planning, the heating systems have developed with low energy efficiency, high environment emission and economic cost. The choice of heating energy structure vary between coal and gas, the heating modes including gas-fired CHP, coal-fired CHP, gas-fired boiler and coal-fired boiler are facing challenges. In this paper, several innovative planning scenarios are proposed to achieve high energy efficiency, low environment emission and reasonable economic cost. In the heating schemes, three innovative technologies are designed. The first technology is waste heat recovery based on the Co-generation-based absorption heat-exchange (Co-ah) cycle. The waste heat can be both from circulating water or flue gas in CHP heating system and the industrial waste heat recovery. The second technology is the heating network with large temperature difference. The third technology is the gas distributed peak-shaving, gas-driven absorption heat-exchange in the substation.

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.

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