Heat Recovery Research Articles

Efficacy of the Direct Anterior Chamber Air Replacement Method During Descemet Stripping Automated Endothelial Keratoplasty.

This study aimed to describe a novel technique of direct anterior chamber (AC) air replacement (DACAR) for the management of Descemet stripping automated endothelial keratoplasty (DSAEK) in postvitrectomized eyes and eyes with previous glaucoma surgery. DACAR was performed after a corneal donor graft was transplanted through a wound using the pull-through technique. DACAR involves stabilizing the graft with forceps while introducing air into the AC via an infusion cannula to ensure complete air exchange. The air was maintained in the AC at all times using a vitrectomy machine. The air pressure was maintained at 30 mm Hg for 15 minutes. The DACAR technique was performed in 34 patients, and conventional pull-through technique DSAEK was performed in 32 high-risk patients. The DACAR group had shorter DSAEK surgical procedures (P = 0.009) and a lower incidence of corneal graft detachment in the early postoperative period (P < 0.001) than the conventional DSAEK group. DACAR is performed in patients having previously undergone vitrectomy or glaucoma surgery to prevent corneal graft detachment during the early postoperative period and to reduce the length of surgery.

Estimation of Radon Flux Density Changes in Temporal Vicinity of the Shipunskoe Earthquake with Mw = 7.0, 17 August 2024 with the Use of the Hereditary Mathematical Model

Using the data of radon accumulation in a chamber with excess volume at one of the points of the Kamchatka subsurface gas-monitoring network, the change in radon flux density due to seismic waves and post-seismic relaxation of the medium is shown. A linear fractional equation is considered to be a model equation. The change of radon-transport intensity due to changes in the state of the geo-environment is described by a fractional Gerasimov–Caputo derivative of constant order. Presumably, the order of the fractional derivative is related to the radon-transport intensity in the geosphere. Using the Levenberg–Marquardt method, the optimal values of the model parameters were determined based on experimental data: air exchange coefficient and order of fractional derivative, which allowed the solving of the problems of radon flux density determination. Data in the temporal neighborhood of a strong earthquake with Mw=7.0, which occurred in the northern part of Avacha Bay on 17 August 2024, were used. As a result of the modeling, it is shown that the strong seismic impact and subsequent processes led to changes in the radon flux in the accumulation chamber. The obtained model curves agree well with the real data, and the obtained estimates of radon flux density agree with the theory.

Revealing the Limitations of the Thermocapacitive Cycle.

While thermoelectric conversion by a thermocapacitive cycle has been considered a promising green technology for low-grade heat recovery, our study finds that its practical feasibility is overestimated. During thermal charging, the coexistence and dynamic competition between thermal-induced voltage rise and self-discharge lead to the limitations of the thermocapacitive cycle. Therefore, the operational conditions in the charge-heat-discharge steps seriously restrict the thermal charging performance. The calculation of energy efficiency further confirms the economic infeasibility of the thermocapacitive cycle. This study provides insights into comprehending the principle and process of thermoelectric conversion by thermocapacitive cycle and will guide the rational development of capacitive heat-to-current converters.

Optimising the Design of a Hybrid Fuel Cell/Battery and Waste Heat Recovery System for Retrofitting Ship Power Generation

This research aims to assess the integration of different fuel cell (FC) options with battery and waste heat recovery systems through a mathematical modelling process to determine the most feasible retrofit solutions for a marine electricity generation plant. This paper distinguishes itself from existing literature by incorporating future cost projection scenarios involving variables such as carbon tax, fuel, and equipment prices. It assesses the environmental impact by including upstream emissions integrated with the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII) calculations. Real-time data have been collected from a Kamsarmax vessel to build a hybrid marine power distribution plant model for simulating six system designs. A Multi-Criteria Decision Making (MCDM) methodology ranks the scenarios depending on environmental benefits, economic performance, and system space requirements. The findings demonstrate that the hybrid configurations, including solid oxide (SOFC) and proton exchange (PEMFC) FCs, achieve a deduction in equivalent CO2 of the plant up to 91.79% and decrease the EEXI and the average CII by 10.24% and 6.53%, respectively. Although SOFC-included configurations show slightly better economic performance and require less fuel capacity, the overall performance of PEMFC designs are ranked higher in MCDM analysis due to the higher power density.

Computational Fluid Dynamics (CFD) Technology Methodology and Analysis of Waste Heat Recovery from High-Temperature Solid Granule: A Review

Computational Fluid Dynamics (CFD) Technology Methodology and Analysis of Waste Heat Recovery from High-Temperature Solid Granule: A Review

Techno-Economic Analysis of Waste Heat Recovery in Automotive Manufacturing Plants

This study proposes an innovative system for recovering waste heat from exhaust air after a regenerative thermal oxidiser process, integrating a Carnot battery and photovoltaic (PV) modules. The Carnot battery incorporates an organic Rankine cycle (ORC) with a recuperator, thermal energy storage (TES), and heat pump. Waste heat is initially captured in TES, with additional energy extracted by a heat pump to increase the temperature of a secondary fluid, effectively charging TES from both direct and indirect sources. The stored heat enables electricity generation via ORC. The result of this study shows a heat pump COP between 2.55 and 2.87, the efficiency of ORC ranging from 0.125 to 0.155, and the power-to-power of the Carnot battery between 0.36 and 0.40. Moreover, PV generates 1.35 GWh annually, primarily powering the heat pump and ORC system pump. The proposed system shows a total annual net generation of 4.30 GWh. Economic evaluation across four configurations demonstrates favourable outcomes, with a return on investment between 25% and 160%. The economic evaluation examined configurations with and without the PV system and recuperation process in the ORC. Results indicate that incorporating the PV system and recuperator significantly increases power output, offering a highly viable and sustainable energy solution.

Thermoelectric Energy Harvesting for Exhaust Waste Heat Recovery: A System Design.

Thermal energy harvesting for high-speed moving objects is particularly promising in providing an efficient and sustainable energy source to enhance operational capabilities and endurance. Thermoelectric (TE) technology, by exploiting temperature gradients between a heat source and ambient temperature, can provide a continuous power supply to such systems, reducing the reliance on conventional batteries and extending operation times. However, the integrated thermoelectric generator (TEG) system design research is far behind materials development. In this study, both experimental and numerical studies of TEG systems are designed and conducted to recover thermal energy. An integrated proof-of-concept platform is developed to simulate an exhaust gas emission system and demonstrate the designed TEG system performance. Triangular plate-fin heat exchangers are designed to collect heat from exhaust pipelines such as engine exhaust gas. While longitudinal trapezoidal fin cylindrical heatsink is designed for dissipating heat via forced convection, particularly for high-speed moving objects, the heatsink design is optimized using finite element analysis (FEA) simulations to maximize the temperature gradient and electrical output power. As a result, under a temperature gradient (ΔT) of 190 °C with commercial bismuth telluride-based TE modules, a maximum system output power of 40 W is achieved experimentally. Furthermore, a computational simulation is conducted to showcase the feasibility of the current system design under high-speed moving vehicle conditions. This study provides an advanced TEG system design bridging the TE device and integrated system transition and represents a potential advancement in the pursuit of high-speed moving objects such as autonomous and longer-lasting aerial platforms.

Preparation and Thermal Performance Study of a Novel Organic-Inorganic Eutectic Phase Change Material Based on Sodium Acetate Trihydrate and Polyethylene Glycol for Heat Recovery.

A novel organic-inorganic eutectic phase change material (PCM) based on sodium acetate trihydrate (SAT) and polyethylene glycol (PEG) was developed to meet the needs of heat recovery and building heating. Three kinds of PEG with different molecular weights were selected to form organic-inorganic eutectic PCM with SAT. The thermal properties of three series of SAT-PEG eutectic PCM were compared based on DSC results, focusing on the impact of PEG addition on the phase change temperature and enthalpy of SAT, as well as the melting uniformity. The inhibitory effects of two nucleating agents on the supercooling of SAT-PEG eutectic PCM were systematically investigated. The effect of PEG on the crystallization behavior of SAT was studied using a metallographic microscope. To evaluate the thermal reliability of the SAT-PEG eutectic PCM, 600 cycles of melting-solidification experiments were conducted. Experimental results show that SAT can form eutectic PCMs with PEG200, PEG600, and PEG6000, respectively, with high enthalpy and excellent melting uniformity. The phase change temperature ranged from 55 °C to 60 °C and the enthalpy was as high as 250-280 kJ/kg. The results of the cooling curves show that 10 wt% tetrasodium pyrophosphate decahydrate (TPD) can reduce the supercooling degree to less than 1 °C. Significantly, all three series of SAT-PEG eutectic PCMs exhibit exceptional thermal reliability after 600 cycles of melting-solidification, with shifts in the phase change temperatures and enthalpies of less than 4%. XRD diffraction patterns showed that SAT, PEG, and TPD were physically mixed without a chemical reaction to form new substances. Microscopic images reveal that the addition of PEG preserves the original needle-shaped crystal morphology of SAT while reducing its crystal size. The rapid formation of small crystals can provide more nucleation points and expedite crystallization, thereby enhancing the heat release capabilities of the PCM.

Oxidant concentrations and photochemistry in a vehicle cabin.

Indoor air quality (IAQ) in vehicles can be important to people's health, especially for those whose occupations require them to spend extensive time in vehicles. To date, research on vehicle IAQ has primarily focused on direct emissions as opposed to chemistry happening in vehicle cabins. In this work, we conducted time-resolved measurements of the oxidants and oxidant precursors ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), and nitrous acid (HONO) inside the cabin of a 2012 Toyota Rav4 under varying ventilation conditions (i.e., car off, car on with passive ventilation, car on with mechanical ventilation via the recirculating fan, and car on with mechanical ventilation via the direct fan). Ozone levels inside the vehicle were significantly lower than outdoors under most conditions, and were approximately half the outdoor levels when the direct fan was in operation. Nitric oxide and NO2 concentrations were very low both inside the vehicle and outdoors. Nitrous acid levels in the vehicle were lower than reported values in other indoor environments, though much higher than expected outdoor levels. We also investigated the potential for photochemical production of radicals in the vehicle. Time- and wavelength-resolved solar irradiance spectra were collected, and steady state hydroxyl radical (OH) and nitrate radical (NO3) concentrations were calculated. Steady state OH concentrations were predicted to be similar to those in air masses in residences illuminated by sunlight, suggesting the importance of HONO photolysis in vehicles. Conversely, nitrate radicals (NO3) were not considered significant indoor oxidants in our study due to rapid titration by NO. Overall, our findings emphasize the importance of both air exchange and photochemistry in shaping the composition of air inside vehicles.

ANFIS-PSO analysis on axisymmetric tetra hybrid nanofluid flow of Cu-CNT-Graphene-Tio2 with WEG-Blood under linear thermal radiation and inclined magnetic field: A bio-medicine application.

The development of heat transfer devices used for heat conversion and recovery in several industrial and residential applications has long focused on improving heat transfer between two parallel plates. Numerous articles have examined the relevance of enhancing thermal performance for the system's performance and economics. Heat transport is improved by increasing the Reynolds number as the turbulent effects grow. Regarding heat transfer, hybrid nanofluids are superior to mono nanofluids. The hybrid fluid of Cu-CNT+Graphene+TiO2/WEG-Blood, which is subject to heat transfer in a channel between two parallel plates with an angled magnetic field and linear thermal radiation, has numerous applications in engineering, industry, and biomedical research, such as electronic cooling, drug delivery, cancer treatment, optics, missiles, satellites, transformer-electronic cooling, and military solar-equipment. Examining the qualities of mass, flow, and heat transmission is the aim of the study of a hybrid Cu-CNT- Graphene-TiO2/WEG-Blood nanofluid as it moves via a tube of porous material that is exposed to linear thermal radiation, inclined magnetic, Forchheimer, and buoyancy influences. ANFIS-PSO model is assumed. Applying the ODE45 integration technique to the given numerical solutions yields non-linear, non-dimensionalized, and highly partial differential equations that control the momentum, energy, and concentration. Consequently, the numerical simulation shows the concentration, velocity, and temperature profiles of the hybrid Cu-CNT- Graphene-TiO2/WEG-Blood nanofluid. A strong concordance is noted between recent and past results. Radiation regulates the microchannel temperature distribution, which significantly contributes to cooling the flow transport system, and the thermal radiation parameter shows that radiation has a retarding influence on the temperature profile.

Multi-Objective Optimisation of a new Multi-Generation System Integrating Waste Heat Recovery, and Geothermal Resources to produce Power, Hydrogen, Heating, and Cooling

Multi-Objective Optimisation of a new Multi-Generation System Integrating Waste Heat Recovery, and Geothermal Resources to produce Power, Hydrogen, Heating, and Cooling

Multi-objective optimization on combined heat pump and mechanical vapor recompression system for waste heat recovery of offshore wind power converter

Multi-objective optimization on combined heat pump and mechanical vapor recompression system for waste heat recovery of offshore wind power converter

Experimental investigation on an advanced thermosiphon-based heat exchanger for enhanced waste heat recovery in the steel industry

Experimental investigation on an advanced thermosiphon-based heat exchanger for enhanced waste heat recovery in the steel industry

Energy storage materials for phase change heat devices recovering industrial waste heat for heating purposes

The abundance of industrial waste heat resources offers valuable opportunities for the utilization of phase change heat exchangers in clean energy applications. This study focuses on the innovative development of binary phase change material (PCM) composed of paraffin and stearic acid (SA) in various ratios, aimed at optimizing waste heat recovery. Comprehensive analyses of the phase change temperature, latent heat, and thermal conductivity of these mixtures were conducted. The research identified a mixture with a 20 % paraffin and 80 % stearic acid ratio, which exhibits a phase change temperature of 62.73 °C and a latent heat of 205.53 J/g. This mixture stands out due to its minimal subcooling and consistent thermal properties, making it highly effective for low-temperature waste heat recovery. Additionally, a novel process design and simulation system for using these materials in heat exchangers to convert intermittent industrial waste heat into continuous thermal energy for heating were developed.

Comprehensive analysis and optimization of an efficient combined power and refrigeration cycle suitable for recovering low/mid-grade waste flue gas

To effectively recover low/mid-grade waste flue gas and provide larger refrigeration capacity, an efficient combined power/refrigeration cycle only using ammonia water as the working fluid is proposed and studied. Parametric analysis is conducted from the perspectives of thermodynamics, exergoeconomics, and environment, the results demonstrate that the low/mid-grade waste flue gas within a wide range of temperature can be sufficiently recovered by the proposed cycle, and the cycle performance is significantly affected by the turbine inlet pressure, work/basic concentration and separation temperature of work solution. Based on the heat source condition of 300°C/10 kg·s-1, the results of single-objective optimization show that the maximum effective exergy efficiency, reduction amount of CO2 emission and waste heat recovery ratio that can be achieved are 0.5989, 262 kg/h and 0.97 respectively, and the achievable minimum unit cost of produced exergy is 8.432 $·GJ-1. Besides, the multi-objective optimization indicates that the optimal comprehensive thermodynamic efficiency is 0.5458 with net power output of 372.5 kW and larger refrigeration capacity of 545.7 kW, and the associated effective exergy efficiency, unit cost of produced exergy, reduction amount of CO2 emission and waste heat recovery ratio are 0.5701, 9.187 $/GJ, 258.3 kg/h and 0.9574, respectively.

Numerical investigation on ash deposition and wear performance of integrally-molded double-sided spiral finned tubes for waste heat recovery

Numerical investigation on ash deposition and wear performance of integrally-molded double-sided spiral finned tubes for waste heat recovery

Performance of a multi-cooling sources cooling system with photovoltaics and waste heat recovery in data center

The establishment of multi-energy cooperative integrated energy system can help data centers achieve sustainable development. This paper proposes a hybrid energy system for data centers, which includes three subsystems: the multi-cooling sources (water-side economizers and ground water) cooling system, the Building Integrated Photovoltaics system (BIPVS) and the waste heat recovery system. Through the coupling of heat and electricity in these subsystems, the proposed hybrid energy system can operate efficiently and low-carbon. A simulation analysis is conducted at a case data center in Nanchang to evaluate the system’s performance in cooling, heating, overall energy efficiency, and economy, by comparing the hybrid energy system with the existing system and isolated energy system. The results indicate that the Coefficient of Performance (COP) of the chiller in hybrid system increases by 0.4 to 2.55 compared to isolated energy system, while the COP of the heat pump increases by 1.4 to 2.1 during heating season. Compared to existing system and isolated system, the hybrid energy system demonstrates potential energy savings of 72.98 % and 21.3 %, respectively, and reduces carbon emissions by 68.34 % and 19.52 %. The dynamic payback period for hybrid energy system is 2.87 years compared to existing system, and 3.54 years compared to isolated system.

Comparison of four layouts of optimized triple-pressure heat recovery steam generator

Comparison of four layouts of optimized triple-pressure heat recovery steam generator

The Evaluation of Thermodynamics and Environmental Impact of Waste Heat Recovery System Using Alternative Refrigerants

The Evaluation of Thermodynamics and Environmental Impact of Waste Heat Recovery System Using Alternative Refrigerants

Cross-scale thermal analysis and comprehensive evaluation of biomimetic skin-flesh composite phase change material for waste heat recovery

Cross-scale thermal analysis and comprehensive evaluation of biomimetic skin-flesh composite phase change material for waste heat recovery