Waste Heat For Production Research Articles

A 7th Law of Thermodynamics and its climate implications

Conversion of the ocean’s vertical thermal energy gradient to electricity via OTEC has been demonstrated at small scales over the past century. It represents one of the planet’s most significant (and growing) potential energy sources. As described here, all living organisms need to derive energy from their environment, which heretofore has been given scant serious consideration. A 7th Law of Thermodynamics would complete the suite of thermodynamic laws, unifying them into a universal solution for climate change. 90% of the warming heat going into the oceans is a reasonably recoverable reserve accessible with existing technology and existing economic circumstances. The stratified heat of the ocean’s tropical surface invites work production in accordance with the second law of thermodynamics with minimal environmental disruption. TG is the OTEC improvement that allows for producing two and a half times more energy. It is an endothermic energy reserve that obtains energy from the environment, thereby negating the production of waste heat. This likewise reduces the cost of energy and everything that relies on its consumption. The oceans have a wealth of dissolved minerals and metals that can be sourced for a renewable energy transition and for energy carriers that can deliver ocean-derived power to the land. At scale, 31,000 one-gigawatt (1-GW) TG plants are estimated to displace about 0.9 W/m2 of average global surface heat into deep water, from where, at a depth of 1000 m, unconverted heat diffuses back to the surface and is available for recycling.

Exploring neighborhood green space to mitigate UHI effect based on a spatial approach in Malang, Indonesia

Urban Heat Island (UHI) is detrimental to climate and ecological conditions. Combined with the UHI effect, this can result in high temperatures; overcrowding worsens UHI due to increased human activity, energy consumption, and waste heat production. This research aims to explore neighborhood green space potential as UHI mitigation. This research uses a spatial approach to explore the configuration of neighborhood and greenspace patterns for UHI mitigation efforts. The research took areas in Malang City. They were selected based on LST values from Sentinel 2 data in the extremely hot, very hot, and near normal categories according to STI (Standardized temperature index). Data collection was carried out using ArcGIS with a spatial approach. The results show a medium greenspace dispersion in the concentrated greenspace category has a potential effort to mitigate UHI. It should be noted that the high and low greenspace dispersion scattered and concentrated greenspace categories are not optimal in mitigating UHI. Future research can look for other factors that can influence UHI mitigation.

Enhancing the Fuel Efficiency of Cogeneration Plants by Fuel Oil Afterburning in Exhaust Gas before Boilers

Cogeneration or combined heat and power (CHP) has found wide application in various industries because it very effectively meets the growing demand for electricity, steam, hot water, and also has a number of operational, environmental, economic advantages over traditional electrical and thermal systems. Experimental and theoretical investigations of the afterburning of fuel oil in the combustion engine exhaust gas at the boiler inlet were carried out in order to enhance the efficiency of cogeneration power plants; this was achieved by increasing the boiler steam capacity, resulting in reduced production of waste heat and exhaust emissions. The afterburning of fuel oil in the exhaust gas of diesel engines is possible due to a high the excess air ratio (three to four). Based on the experimental data of the low-temperature corrosion of the gas boiler condensing heat exchange surfaces, the admissible values of corrosion rate and the lowest exhaust gas temperature which provide deep exhaust gas heat utilization and high efficiency of the exhaust gas boiler were obtained. The use of WFE and afterburning fuel oil provides an increase in efficiency and power of the CPPs based on diesel engines of up to 5% due to a decrease in the exhaust gas temperature at the outlet of the EGB from 150 °C to 90 °C and waste heat, accordingly. The application of efficient environmentally friendly exhaust gas boilers with low-temperature condensing surfaces can be considered a new and prosperous trend in diesel engine exhaust gas heat utilization through the afterburning of fuel oil and in CPPs as a whole.

THERMOELECTRIC POWER GENERATION FROM WASTE HEAT OF GAS STOVE BY USING THE THERMOELECTRIC GENERATOR

The objective of this research is set to produce energy by utilizing the unused heat of gas stove through thermoelectric generator. Currently, an increasing concern of environmental issues of emissions like greenhouse effects and the scarcity of fossil fuel has resulted in extensive research into the alternative ways of generating electrical power. Thermoelectric power generator has been considering as one of the promising alternatives due to its advantages. The application of this alternative option in converting waste-heat energy directly into electrical power that may also enhance the overall efficiencies of energy conversion systems. In this study, a gas burner was set to generate electricity that will produce waste heat. One thermoelectric unit is installed underneath the burner cap of the gas burner. Gas flame at the edge of the burner cap creates heat sources (hot side) for the thermoelectric unit. A gas-mixing chamber underneath the thermoelectric unit functions as heat sink (cold side) for the thermoelectric unit. An insulation plate is inserted in between the thermoelectric unit and the burner cap to control the hot side temperature. The thermoelectric unit generates electricity while the gas burner is in use and the flame heats up the burner cap. The thermoelectric unit connects to an electric circuit and provides electricity to power devices.

Decarbonisation of heat: Analysis of the potential of low temperature waste heat in UK industries

The UK will need to decarbonise low temperature industrial waste heat (up to ≈250 °C) to achieve net-zero greenhouse gas emission targets. Industrial waste heat production represents an opportunity for reduction in the use of primary fuels used in the production of commodities. Energy inefficient processes in addition to increased emissions raises the cost of plant operation, – an undesirable scenario for both industrial competitiveness and the environment. Less is known about the quantity and potential applications for recovered low temperature industrial waste heat in UK and the quantification and characterisation of the resource can provide the needed impetus for the development and adoption of green technologies to help achieve the 2050 Net-Zero target. In this work the potential magnitude of the low temperature industrial waste heat resource in the UK is analysed by using sector-level energy intensity values for different industries while drawing on corresponding estimates from previous studies in the USA and by closely mapping the UK Standard Industrial Classification (SIC 2007) against sectors in the USA (NAICS [North American Industry Classification System]). The assessment undertaken finds that the recoverable potential of low temperature waste heat up to ≈250 °C could be up to 83.7% of the total estimated waste heat potential in UK industry. Significant opportunities exist in this low temperature range for waste heat recovery actions at individual sites. Research and Development (R&D) into alternative improved methods for waste heat recovery, storage, and use (WHRSU) technologies could also produce significant positive environmental and industrial impact.

A Review: Urban Heat Island and its Impact on Building Energy Consumption

Civilization and urbanization are the two key demands of humans in the 20th century. Over the last few decades, a considerable number of the human population have moved to urban areas. This phenomenon has led to an explosion of the population in some of the major cities around the globe, including in Saudi Arabia. Urban Heat Island (UHI) is a climatic condition in which urban settlements experience increased air temperature than their neighboring rural counterparts. The UHI is attributed to the anthropogenic modification of land surfaces, population growth, urban development, and its consequential production of waste heat, which is endangering human health and the environment as well as the quality of living. Series of factors have been responsible for UHI, including building orientation, material albedo, land use, high-rise constructions, and human activities. The present study investigates the significance of the UHI features and their relation to building energy consumption. A list of contributing factors to UHI was identified and analyzed. The study suggests that there is a positive relationship between urban greening and urban material concerning energy consumption. Thus, this is a potential study gap that needs to be addressed to analyze the impact of UHI, particularly in the context of Saudi Arabia.

Recent Studies on the Environmentally Benign Alkaline-Earth Silicide Mg2Si for Middle-Temperature Thermoelectric Applications

Most primary energy sources, such as the fossil fuels of oil, coal, and natural gas, produce waste heat. Recycling of this unused thermal energy is necessary in order to increase the efficiency of usage. Thermoelectric (TE) conversion technologies, by which waste heat is directly converted into electricity, have been extensively studied, and the development of these technologies has continued. TE power-generation has attracted significant attention for use in self-powered wireless sensors, which are important for our increasingly sophisticated information society. For the middle-temperature range (i.e., 600–900 K), with applications such as automobiles, intensive studies of high-performance TE materials have been conducted. In this study, we review our recent experimental and theoretical studies on alkaline-earth silicide Mg2Si TE materials, which consist of nontoxic abundant earth elements. We demonstrate improvements in TE performance brought about by lightly doping Mg2Si with isoelectronic impurities. Furthermore, we examine the electrode formation and material coatings. Finally, we simulate the exhaust heat requirements for the practical application of TE generators.

Explorative study on waste heat production intensity and recovery practices in the textile sector: First steps towards the creation of a decision support tool based on real data

Nowadays industrial companies are getting more and more aware of the fact that a huge amount of the energy consumed every year goes unused and lost in the form of waste heat. Despite the fact that awareness is raising, incentives are available and that waste heat recovery technologies are generally mature and market-ready, heat recovery measures are still unimplemented at industrial level, mainly due to non-technological barriers, and in particular to the lack of reliable data related to heat consumption and waste heat recovery potentials, as well as to types, costs and benefits of heat recovery practices. The aim of this work is to fill such informational gap for the textile sector, providing a knowledge base elaborated on the basis of real industrial data gathered via a massive survey, and allowing further elaborations from the authors and academics. ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic development, has in fact seized the opportunity to gather a relevant amount of data related to heat consumption, uses, potentials and recovery practices on the second deadline imposed by the Italian Legislative Decree n°102 of the July 4, 2014, which established periodic mandatory energy audits for large and energy intensive enterprises. Methodology and main results of data analysis are presented, providing a solid basis for both companies willing to identify and evaluate potential heat recovery opportunities for their processes, thus enabling knowledge transfer and practices sharing, and academics and policy makers willing to estimate recovery potentials. Consumption data for the textile sector are presented together with the quantification of main heat uses, allowing the identification of most relevant sub-sectors in terms of waste heat potential; heat recovery practices described in the energy audits are then analysed and characterized from a technical and economic point of view.

New machine functions using waste heat recovery: A case study of atmospheric pressure plasma jet

Intelligent machines, the cornerstone of Industry 4.0, possess various sensors for monitoring key processing and environmental parameters. These sensors demand additional power, while the machines often produce waste heat. Hence, we propose using a thermoelectric generator (TEG) to recover the waste heat and generate electricity to drive these sensors. A standard design for an atmospheric pressure plasma jet (APPJ) is demonstrated in this work. A so-driven multi-functional monitoring system monitors the processing temperature of the APPJ and air quality in the surroundings, transmits the data to cloud storage, and alarms if the temperature or air quality exceeds a preset value. We study three different arrangements of TEGs and find that double TEGs connected in series thermally and electrically generate the most power of 1.09 ± 0.0002 W at a current of 0.187 ± 0.002 A, which is sufficient to drive the monitoring system continuously. We also perform three-dimensional finite element transient thermal simulations to pre-assess the detailed temperature distribution for film-quality control and the potential for power generation. Our method can be readily applied to other machines with high waste heat for adding sensors/actuators without consuming extra power.

Thermal Management Systems and Waste Heat Recycling by Thermoelectric Generators—An Overview

With the fast evolution in greenhouse gas (GHG) emissions (e.g., CO2, N2O) caused by fossil fuel combustion and global warming, climate change has been identified as a critical threat to the sustainable development of human society, public health, and the environment. To reduce GHG emissions, besides minimizing waste heat production at the source, an integrated approach should be adopted for waste heat management, namely, waste heat collection and recycling. One solution to enable waste heat capture and conversion into useful energy forms (e.g., electricity) is employing solid-state energy converters, such as thermoelectric generators (TEGs). The simplicity of thermoelectric generators enables them to be applied in various industries, specifically those that generate heat as the primary waste product at a temperature of several hundred degrees. Nevertheless, thermoelectric generators can be used over a broad range of temperatures for various applications; for example, at low temperatures for human body heat harvesting, at mid-temperature for automobile exhaust recovery systems, and at high temperatures for cement industries, concentrated solar heat exchangers, or NASA exploration rovers. We present the trends in the development of thermoelectric devices used for thermal management and waste heat recovery. In addition, a brief account is presented on the scientific development of TE materials with the various approaches implemented to improve the conversion efficiency of thermoelectric compounds through manipulation of Figure of Merit, a unitless factor indicative of TE conversion efficiency. Finally, as a case study, work on waste heat recovery from rotary cement kiln reactors is evaluated and discussed.

Dry Surface Treatment Technology for the Design of the Anode Side of the Metal Support Solid Oxide Fuel Cell (MS-SOFC)

As an electrochemical energy conversion device, solid oxide fuel cell (SOFC) has many advantages in energy conversion efficiency, fuel flexibility and environmental benefits. A typical high temperature SOFC possesses the advantages of high power density and high-grade waste heat production. However, high-temperature SOFC faces challenges in cost and long-term durability. Once the operating temperature of SOFC is effectively reduced, the fuel cell configuration anode supported can be changed to metal-supported SOFC (MS-SOFC). Alternative MS-SOFC designs have the advantages of low-cost material, robustness and convenient manufacturing.In the present work, the metal supported half-cell with ITM / protective layer / Ni-YSZ / YSZ / GDC configurations were elaborated. Three protective layers of Co, Ce/Co and GDC were compared in terms of preventing Cr diffusion. Reactive magnetron sputtering (RMS) was used to deposit the electrolyte and the barrier layer because it can easily achieve a dense adherent and thin film. Atmospheric plasma spraying (APS) was used to deposit the cermet Ni-YSZ anode layer to facilitate the formation of porous structures. The morphology, microstructure and chemical composition of MS-SOFC were characterized by SEM, XRD and EDX, respectively. Finally, its electrical characteristics were measurements by four probe electrical and electrochemical impedance spectroscopy measurements.

Management of a district heating network using model predictive control with and without thermal storage

District heating and cooling networks are a key infrastructure to decarbonise the heating and cooling sector. Besides the design of new networks according to the principles of the 4th and 5th generation, operational aspects may significantly contribute to improve the efficiency of existing networks from both economic and environmental standpoints. This article is the second step of a work that aims to exploit the flexibility of existing networks and improve their economic and environmental performance, using the district heating network of Verona as a case study. In particular, the first part of the research demonstrated through numerical simulations that the thermal inertia of the water contained in the pipes can be used to shift the heat production of the generators over time by acting on the flow rate circulating in the network. This article shifts the focus from the heat distribution side to the heat supply. A model predictive control strategy was formulated as a MILP optimization problem to schedule the heat supply of the cogeneration plants, heat pump and gas boilers as a function of heat load, waste heat production and electricity price forecasts. Computer simulations of considered district heating network were carried out executing the optimization with a rolling-horizon scheme over two typical weeks. Results show that the proposed look-ahead control achieves a reduction in the operational costs of about 12.5% and 5.8%, respectively in a middle season and a winter representative week. Increasing the flexibility of the system with a centralized heat storage tank connected to the CHP and HP units, these percentage rise to respectively 20% and 6.3%. In the warmest periods, when the total installed power of the CHP and HP plants is sufficient to supply the entire heat demand during the peak, and the modulation of these plants has a higher impact, the cost reduction related to the additional thermal energy storage is more relevant.

Potential carbon emissions reduction related to the recovery of unutilised waste heat

The introduction of district heating will have a significant impact on the building services industry, from the architecture of a building to its operation. This technical note investigates a delimited portion of the potential of currently unutilised heat which has the possibility to supply district heating networks in the UK. The UK industrial sector, wastewater treatment facilities and the existing UK waste incineration plants all produce waste heat available in a temperature range suitable for extraction into district heating networks via commercialised techniques broadly used in other countries. This technical note presents a comparative literature review, comparing UK statistics and studies with performance data based on Swedish operational facilities. It finds 51.7TWh of currently unutilised heat could be recovered annually, with a significant associated emission decrease if incorporated into the heat supply of the UK building stock. A quantitative analysis is carried out to compare the identified potential with the current UK heat demand and the potential impact on the UK carbon emissions is estimated. The calculations indicate a reduction of 14% in the required UK total domestic heat supply, despite only including a limited fraction of the available waste heat potential. Practical application: This technical note serves to highlight and emphasise the large amount of available waste heat potential currently not utilised in the UK. By estimating the impact of waste heat utilisation and incorporation into district heating and heat networks in the UK, the technical note aims to fuel discussion around the further incorporation of waste heat to be utilised in the UK heat sector.

Energy, economic, and environmental analysis of integration of thermal energy storage into district heating systems using waste heat from data centres

Data centres produce waste heat, which can be utilized in district heating systems. However, the mismatch between data centres’ heat supply and district heating systems’ heat demands limits its utilization. Further, high peak loads increase the operation cost of district heating systems. This study aimed to solve these problems by introducing thermal energy storages. A water tank and a borehole thermal energy storage system were selected as the short-term and long-term thermal energy storage, respectively. Energy, economic, and environmental indicators were introduced to evaluate different solutions. The case study was a campus district heating system in Norway. Results showed that the water tank could shave the peak load by 31% and save the annual energy cost by 5%. The payback period was lower than 15 years when the storage efficiency remained higher than 80%. However, it had no obvious benefits in terms of mismatch relieving and CO2 emissions reduction. In contrast, the borehole thermal energy storage increased the waste heat utilization rate to 96% and reduced the annual CO2 emissions by 8%. However, the payback period was more than 17 years. These results provide guidelines for the retrofit of district heating systems, where data centres’ waste heat is available.

Waste Heat to Power: Technologies, Current Applications, and Future Potential

Energy consumption, environmental impact, and sustainability have risen fast through the ranks, achieving the first places in driving investments, policies, and concerns of all countries at any developmental stage. Energy transformation, though, must cope with nonunitary efficiency of devices and processes, which results in a distributed production of waste heat. A reduction of emissions, implying a conversion of waste heat to more noble forms of energy and a concurrent increase in efficiency of the same devices and processes, is of paramount importance. In view of the enthalpy content and distribution of the different sources of waste heat, low‐grade/low‐enthalpy sources below 200 °C are considered the most fertile field for research and development, with an impressive industrial growth rate. Thermodynamic cycles and thermal conversion devices based on the most relevant physical effects are herein introduced and briefly described, including both solutions that already achieved industrial maturity and less developed systems and devices whose study is still in progress. A specific focus on three application domains, selected due to their economic relevance, is done: industrial processes for the vast energy and capital availability, automotive sector for its permeation, and wearable devices for the market size. Limits and opportunities are critically discussed.

Triboelectric Characterization of Colloidal TiO2 for Energy Harvesting Applications.

Nowadays, energy-related issues are of paramount importance. Every energy transformation process results in the production of waste heat that can be harvested and reused, representing an ecological and economic opportunity. Waste heat to power (WHP) is the process of converting the waste heat into electricity. A novel approach is proposed based on the employment of liquid nano colloids. In this work, the triboelectric characterization of TiO2 nanoparticles dispersed in pure water and flowing in a fluorinated ethylene propylene (FEP) pipe was conducted. The idea is to exploit the waste heat to generate the motion of colloidal TiO2 through a FEP pipe. By placing an Al ring electrode in contact with the pipe, it was possible to accumulate electrostatic charges due to the triboelectric effect between the fluid and the inner pipe walls. A peristaltic pump was used to drive and control the flow in order to evaluate the performances in a broad fluid dynamic spectrum. The system generated as output relatively high voltages and low currents, resulting in extracted power ranging between 0.4 and 0.6 nW. By comparing the power of pressure loss due to friction with the extracted power, the electro-kinetic efficiency was estimated to be 20%.

Sistem Kendali Distribusi Gas Buang pada Waste Heat Recovery Power Generation untuk dikonversi menjadi Energi Terbarukan di Indarung V, PT. Semen Padang, Indonesia

The coal combustion processes which require high temperature will produce waste heat energy. The energy can be used as generator propulsion to produce electrical energy. Thus, Semen Padang Corporation has successfully got funding from the Japan government, New Energy Technology Development Organization (NEDO) to build the installation Waste Heat Recovery Power Generation (WHRPG) located in the production area of Semen Padang Corporation, Indarung V. Furthermore, heat energy process can not be operated manually, so control system is needed to control this WHPRG performance. The operational of WHPRG can produce electricity power 196.15 MW as to reduce the electric power that must be supplied by Indonesian Electricity Corporation. Besides that, the outcome of Semen Padang Corporation can be saved 33 billion Rupiah per year and CO2 emission can be declined 33,000 tons per year. 

Thermodynamic analysis of cooling and heating systems for energy recovery

Abstract All energy systems that produce waste heat that is above the ambient temperature, must be coupled to other thermal equipment in order to increase the benefits of the primary source and, like this, reduce pollution. By means of the first and second law of thermodynamics, this work analyses waste heat recovery of a Two Stage Vapour Compression System (R123) for an Absorption Heat Transformer (H2O/LiBr). Both systems are evaluated in an individual and comprehensive manner, considering an evaporation temperature of 235.15 K in the condenser of the cooling system and different absorption temperatures in the heating system. The cooling system (by means of the condenser) is capable of reaching the temperatures required to activate the heating system (through the evaporator); however, its energy performance decreases and exergy destruction increases in the high-pressure circuit. Two relationships are proposed to quantify the performance of the coupled machines, where recovered heat and its temperature play an important role. Under this analysis scenario, it is possible to reach performance values of the coupling from 0.711 to 0.927, when the difference in the absorber and evaporator temperatures decreases by 18 K at an interchange temperature of 343.15 K.

Waste-to-hydrogen: Recycling HCl to produce H2 and Cl2

Coal-fired power plants are the most common form of power generation in many regions, which continuously produce waste heat and hydrogen chloride (HCl) flue gas. To address this issue, a novel Cu-Cl hydrogen production cycle is modeled to recycle industrial waste heat and exhaust HCl and to produce hydrogen, realizing the waste-to-hydrogen (WtH) process. To complement the process analysis, a gate-to-gate life cycle emission analysis and gate-to-grave cost-benefit analysis have been performed to evaluate the commercial feasibility and environmental impacts. The final results of the product cost and life cycle CO2 emission of this Cu-Cl cycle are 2.8 US dollars/kg H2 and 8.7 kg CO2/kg H2, respectively. Cu-Cl cycle offers an economically competitive option compared with the steam methane reforming (SMR) hydrogen production process if taking the benefit of Cl2 into account. The life cycle CO2 emission of the Cu-Cl cycle is less than other existing processes, as the process can consume a considerable amount of HCl gas, which is regarded as greenhouse gas as well. The proposed process is shown to be a promising alternative to conventional hydrogen production processes.

High efficiency SNG production from biomass and electricity by integrating gasification with pressurized solid oxide electrolysis cells

Co-electrolysis of CO2 and H2O in pressurized solid oxide electrolysis cells (SOEC) results in internal methanation when the fuel electrode contains nickel, as nickel catalyzes the methanation reaction. Recent SOEC stack experiments operated at 19 bar and 700 °C produced a gas with a methane content of 18 vol% (dry). The exothermic methanation reaction is a perfect match for the endothermic electrolysis reactions, enabling an overall slightly exothermic stack operation at a moderate polarization voltage. When using a pressurized SOEC for biomass syngas upgrading to synthetic natural gas, it is possible to achieve very high energy efficiency because a high share of the exothermic methane formation can occur inside the SOEC. The production of waste heat from the downstream methanation reactor is therefore reduced significantly. In this paper, such an integrated system design is proposed and evaluated by thermodynamic modelling and analysis. The analysis shows that the proposed system can reach 84% energy efficiency from wood pellets and electricity to synthetic natural gas. This is substantially higher than the ∼70% efficiency than can be achieved with steam electrolysis based systems. If steam drying is integrated to allow the use of wet wood chips, the efficiency drops to 82%.