Analysis and Prospect of Waste Heat Utilization from Blast Furnace Slag Flushing

Estimating the residual heat of blast furnace slag flushing in China,classifying and introducing the current proposed methods of slag flushing waste heat utilization,and listing existing cases.In order to better save energy and water in the slag flushing process of blast furnaces,an ideal comprehensive cascade utilization system scheme for annual recovery of waste heat is proposed.Based on the measured waste heat data of a steel plant,design calculations are carried out to further analyze the economic feasibility of the new scheme and provide reference for its promotion and application.

Diesel generator exhaust heat recovery fully-coupled with intake air heating for off-grid mining operations:An experimental,numerical,and analytical evaluation

The customarily discarded exhaust from the fossil fuel-based power plants of the off-grid mines holds the thermal potential to fulfill the heating requirement of the underground operation.This present research fills in an important research gap by investigating the coupling effect between a diesel exhaust heat recovery and an intake air heating system employed in a remote mine.An integrative approach comprising analytical,numerical,and experimental assessment has been adapted.The novel analytical model developed here establishes the reliability of the proposed mine heating system by providing comparative analysis between a coupled and a decoupled system.The effect of working fluid variation has been examined by the numerical analysis and the possible improvement has been identified.Experimental investigations present a demonstration of the successful lab-scale implementation of the concept and validate the numerical and analytical models developed.Successful deployment of the fully coupled mine heating system proposed here will assist the mining industry on its journey towards energy-efficient,and sustainable mining practices through nearly 70%reduction in fossil fuel consumption for heating intentions.

Performance Analysis of an Integrated Supercritical CO_(2) Recompression/Absorption Refrigeration/Kalina Cycle Driven by Medium-Temperature Waste Heat

A novel power and cooling cogeneration system which combines a supercritical CO_(2) recompression cycle(SCRC), an ammonia-water absorption refrigeration cycle(AARC) and a Kalina cycle(KC) is proposed and investigated for the recovery of medium-temperature waste heat. The system is based on energy cascade utilization, and the waste heat can be fully converted through the simultaneous operation of the three sub-cycles. A steady-state mathematical model is built for further performance study of the proposed system. When the exhaust temperature is 505℃, it is shown that under designed conditions the thermal efficiency and exergy efficiency reach 30.74% and 61.55%, respectively. The exergy analysis results show that the main exergy destruction is concentrated in the heat recovery vapor generator(HRVG). Parametric study shows that the compressor inlet pressure, the SCRC pressure ratio, the main compressor and the turbine I inlet temperature, and the AARC generator pressure have significant effects on thermodynamic and economic performance of the combined system. The findings in this study could provide guidance for system design to achieve an efficient utilization of medium-temperature waste heat(e.g., exhaust heat from gas turbine, high-temperature fuel cells and internal combustion engine).

A simultaneous approach for integration of thermal energy storages in industrial processes using multiperiod heat integration

In times of increasing global warming,enormous efforts are required to rapidly reduce greenhouse gas(GHG)emissions.Due to the EU’s target of climate neutrality by 2050 and the even more ambitious goal of becoming climate-neutral in Germany by 2045,it is necessary to systematically increase energy efficiency and decarbonize the industrial heat sector.The methods of heat integration can be used to exploit existing potentials for waste heat utilization and to integrate renewable technologies for heating and cooling.By using a non-stationary,multiperiod approach,additional energy savings can be achieved by integrating a thermal energy storage(TES)that enables heat transportation over time.This paper presents a simultaneous approach for thermal energy storage integration into multiperiod heat integration problems.The approach can be used to minimize energy demand,costs and CO 2 emissions and is demonstrated in two case studies.In case study 1,it is shown that the presented approach is capable of integrating a TES properly into a simple multiperiod heat integration problem with two periods.In case study 2,a simplified example from a cosmetics manufactory is investigated.The total utility demand can be reduced by up to 44.3%due to TES integration and the energetic optimal storage size can be determined as 125 m 3.The savings are strongly dependent on the constellation of heat flows between the periods,on the temperature levels and on the storage size.Significant reductions of energy demand,costs and CO 2 emissions can be achieved with TES being properly integrated into a suitable operating environment.

Nanofluidic osmotic power generation from CO_(2) with cellulose membranes

The diffusion of chemical species down concentration gradient is a ubiquitous phenomenon that releases Gibbs free energy.Nanofluidic materials have shown great promise in harvesting the energy from ionic diffusion via the reverse electrodialysis process.In principle,any chemicals that can be converted to ions can be used for nanofluidic power generation.In this work,we demonstrate the power generation from the diffusion of CO_(2) into air using nanofluidic cellulose membranes.By dissolving CO_(2) in water,a power density of 87 mW/m^(2) can be achieved.Using monoethanolamine solutions to dissolve CO_(2),the power density can be increased to 2.6 W/m^(2).We further demonstrate that the waste heat released in industrial and carbon capture processes,can be simultaneously harvested with our nanofluidic membranes,increasing the power density up to 16 W/m^(2) under a temperature difference of 30°C.Therefore,our work should expand the application scope of nanofluidic osmotic power generation and contribute to carbon utilization and capture technologies.