Because of the continuous expanding of the district heating, the heating load of combined heat and power (CHP) plants increases year by year. The minimum power load of CHP plant increases with the heating load due to the heat-power coupling mechanism. Therefore, heat-power decoupling is necessary to improve the operation flexibility for CHP units. Integrating the absorption heat pump (AHP) is an effective method to realize the heat-power decoupling. In this study, a 330MW CHP unit model and AHP model have been developed and validated. The performance of the heat-power decoupling and energy saving performance has been investigated by comparing the thermodynamic performance indicators. Results show that, the proposed system can increase the maximum heating load and decrease the power generation when the primary network return temperature is decreased. When the heating steam extraction is kept constant, with the increase of the primary network return water temperature, the heat generation efficiency and the standard coal consumption rate of heating increases, the coal consumption rate of power generation and the heating efficiency decreases. And the primary network return water temperature increases from 40 °C to 70 °C, the coal consumption rate of power generation decreases by 4.3 g/kWh, and the coal consumption rate of heating increases by 0.67 kg/GJ.

The environmental conditions (air temperature and relative humidity) have a great impact on the power and efficiency of gas turbine combined cycle (GTCC) system. Using the intake air cooling technology can greatly improve the performance of GTCC system. On the base of the PG9351FA gas turbine combined cycle system, this article builds the models of both the GTCC system and a typical lithium bromide absorption refrigeration system using Aspen Plus software. The effects of compressor inlet air cooling with different environmental conditions on the GTCC system performance are studied. The research results show that using the inlet air cooling technology can obviously increase the output powers of both the gas turbine and the combined cycle power. When the ambient humidity is low, the efficiency of GTCC changes gently; while the ambient humidity is high, the GTCC system efficiency will decline substantially when water in the air is condensed and removed with the progress of cooling process. At the same ambient temperature, when the relative humidity of the environment is equal to 20%, the gas turbine output power is increased by 35.64 MW, with an increase of 16.32%, and the combined cycle output power is increased by 39.57 MW, with an increase of 11.34%. At an ambient temperature of 35°C, for every 2.5 °C drop in the compressor inlet air, the thermal efficiency of the gas turbine increases by 0.189% compared to before cooling.

This paper addresses the potential of integrating the existing oil wells and absorption chiller for the purpose of provision space cooling for the base camp of oil field at Block 9 located in Oman. The wellbore was used as a hot water feed to the chiller. Well S 347 was selected as the hot water source and well S 179 was selected to be the injection well for the outlet water. The existing wells were assessed via PIPESIM software. Using PIPESIM software, the fluid temperatures, well pressure and flow rates were obtained and analyzed throughout NODAL analyses. The water temperature of 100 °C, well head pressure of 100 psi and flow rate of 30 m 3 /h, were found to be the optimum operating parameters. The COP of the absorption chiller was obtained via ABSIM software. The variable operating conditions were investigated and elaborated as a function of the efficiency and capacity ratio. The designed system was configured to yield 0.733 COP and a capacity of 377 KW which met the cooling capacity of the admin building of block 9. The entire feasibility analysis was performed in terms of the overall cost as well as the saving that would be achieved from such homogeneity. The payback period of the entire system was found to be 7 years which emphasized a great potential of adapting the technology if the operating resources are available.

Desalination is becoming a popular and necessary process for producing fresh water in deserts and areas across the word affected by drought. Small Modular Reactor (SMR) technology is attractive for this application because it cogenerates steam and electricity to run multiple desalination processes at once. Multi-Effect Distillation (MED) technology requires steam to evaporate fresh water, while Reverse Osmosis (RO) only requires electricity for desalination. While RO typically produces fresh water more efficiently than MED, condensate from the evaporators can be flashed and sent to an absorption chiller to produce chilled water for space cooling. This study uses a 6-effect backward feed evaporator model to analyze revenues and savings from total freshwater and chilled water produced and determine the steam pressure from the SMR and loading schedule to produce maximum revenue for the specified desalination facility. Three loading schedules were chosen for this study: base loading, day/night loading, and diurnal demand loading, and revenues were calculated by closely matching a demand of 50,000 people. Day/night loading resulted in significantly more revenue and chilled water production than the other two schedules. The coupling of RO and MED systems to a small modular reactor could result in increased revenue for a desalination plant while meeting the freshwater demands of a community.

In order to pursue superior cycle efficiency and lower power generation cost for the CSP plants, two S-CO 2 –Brayton–cycle–based power cycles with different utilization methods of the residual heat recover of the top S-CO 2 Brayton cycle (SCBC) are investigated to seek alternatives to the stand-alone S-CO 2 cycle as the power block of concentrated solar power plants. The residual heat released by the top S-CO 2 cycle are either utilized to drive a LiBr absorption chiller (AC) for further chilling of the CO 2 fluids exiting the precooler before entering the main compressor inlet temperature or recovered by an organic rankine cycle (ORC) for generating electricity. Thermo-economic analysis and optimization are performed for the SCBC–AC and SCBC–ORC, respectively. The results show that the thermal and exergetic efficiencies of the SCBC–AC are comparable with those of the SCBC–ORC in low pressure ratio conditions ( PR <2.7) but are apparently lower than SCBC–ORC when PR is over 2.7. The LCOE of the CSP plant integrated with SCBC–AC is more sensitive to the change of PR . The optimal PR to maximum the cycle efficiency or minimize the plant LCOE for the SCBC–ORC is higher than that for the SCBC–AC, while the optimal recuperator effectiveness to minimize the LCOE of CSP plant integrated with SCBC–ORC is lower than that of SCBC–AC. The optimization results show that the thermo-economic performance of the SCBC–AC is comparable to that of the SCBC–ORC. Significant η ex improvement and LCOE reduction can be obtained by both the two combined cycles relative to the stand-alone S-CO 2 cycle. The maximal η ex improvements obtained by the SCBC–ORC and SCBC–AC are 6.83% and 4.12%, respectively. The maximal LCOE reduction obtained by the SCBC-ORC and SCBC–AC are 0.70 ȼ / (kW·h) and 0.60 ȼ / (kW·h), respectively.

The trace element mercury (Hg 0 ) released from fossil fuel combustion in thermal power plants is difficult to be collected by pollution control equipment as its high volatility, high volatility and low solubility. The removal of Hg 0 is the most critical part of mercury removal technology. The existing technologies of mercury removal include activated carbon adsorption, fly ash adsorption, calcium-based adsorbent adsorption, and wet scrubbing method. While these existing technologies have some disadvantages, like high absorbent consumption, high absorption cost and existence of secondary pollution. Much attention has been devoted to the development of new mercury removal technology in recent years. In this study, the Ca(ClO) 2 solution was proposed for the absorption of elemental mercury as its strong oxidizing property and low expenditure. The chemical reaction mechanism, reaction kinetics and reaction thermodynamic in both absorption and regeneration processes were explored, which verified the feasibility of mercury removal and absorbent regeneration. Effects of solution concentration, absorption temperature and solution pH value on absorption performance of Ca(ClO) 2 solution were investigated in micro bubbling reactor. The experimental results revealed that acid environment (pH = 1–5) and high solution concentration were beneficial to mercury removal. A high removal efficiency (over 90%) and a low outlet mercury concentration (below 0.01mg·m 3 ) was obtained under optimal experimental parameters (with the pH value of 3, the solution concentration of 15 mmol·L −1 and the temperature of 25 °C). The performance of electrolytic regeneration in Ca(ClO) 2 rich solutions were carried out, and the effect of electrolysis time on current efficiency and energy consumption in electrolytic regeneration processes were specifically studied. The regeneration results showed that the oxidation reaction of Cl − with a series of other oxidation reactions will occur at the anode, and the reduction reaction of Hg 2+ will occur at the cathode. The results verified the feasibility of the electrolytic regeneration of Ca(ClO) 2 rich solution using an ion-exchange membrane insulating the catholyte and the anolyte. The Ca(ClO) 2 solution is a promising absorbent for elemental mercury which can accomplish the cyclic utilization of solution and the reuse of mercury.

A large number of Xinjiang Zhundong coal was found in China. Its high content of alkali metals can cause serious fouling/slagging problems which may lead to economic losses. It is significant to control the release of alkali metals from Zhundong coal during the combustion. Si-Al additives are used to capture Na released from the Zhundong coal. In this work, a combination of experimental research and quantum chemical calculation was used to study the effect of coal ash on the capture of alkali metal in Zhundong high alkali Coal and the related mineral evolution mechanism during melting processes. The experiments were done with Zhundong coal/coal ash mixtures at 900–1200°C. The behavior mechanism of coal ash capturing alkali metals was analyzed from the perspective of mineral microstructure features by using XRD, ICP and quantum chemical calculation methods. The results show that during the process of combustions, complex chemical reactions occur among minerals after sodium is released from the coal and captured by the coal ash. The coal ash’s ability to capture sodium in Zhundong high alkali coal rises firstly, and then gradually decreases with the rise of temperature. It shows the best capture performance for sodium at 1000∼1100°C. The maximum efficiency of sodium absorption can reach to 50.6%. The coal ash shows a rather high efficiency compared with other additives. Furthermore, metals in Zhundong coal have opposite directions of migration. The Na, K, Al, Ca, and Mg migrated to the coal ash far away from the reaction interface, and the Fe and Mn were moved to the coal from the reaction interface. The original minerals of Zhundong coal mainly include calcium sulfate hydrate, quartz and kaolinite. Investigating the capture mechanism, it indicates that O (26) and O (22) in kaolinite have electrophilic reaction with Na+ and K+ easily, which would promote the rupture of aluminum-oxygen bonds. The O2- of alkali metal or alkaline earth metal oxide would easily have nucleophilic reaction with Si (6) and Si (8) and prompt the rupture of bridging oxygen bonds (Si-O-Si). Kaolinite would be transformed into some other minerals that contains Na+ or K+ which have trend to form eutectics or evaporate into the flue gas easily, the degree of fouling and slagging on heating surface can be reduced based on these two most easily reaction paths.

A modified sorbent was prepared by a novel hydration-impregnation method. Results indicated that hydrating with salt water can obtain enhanced capacity of the sorbents during multiple calcination/carbonation reactions. After 40 cycles, the modified limestone sorbent doped with 2wt% lake salt remained a CO 2 capture capacity of 0.34 g of CO 2 of sorbent, which was 150% higher than that of natural limestone. XRF and XRD were tested for analyzing the chemical component of the sorbents. A Fixed-bed reactor was applied to test the absorption characteristics of those sorbents. SEM analysis revealed that macropores in this novel sorbent were relatively stable during long-term cycles. A preliminary economic analysis of different modified calcium-based sorbents was conducted, and the results demonstrated that limestone modified by lake salt is a promising scheme for large-scale sorbent production, which is a well cost-effective and pollution free scenario suitable for industrial promotion. (CSPE)

Solar water heaters (SWHs) are a well-established renewable energy technology that have been widely adopted around the world. In this study we have significantly improved the Evacuated Tube solar Collectors (ETCs) by utilizing the “dry-drawable” Carbon Nanotube (CNT) sheet coatings to increase the solar energy absorption and Phase Change Materials (PCMs) to increase the heat accumulation for application in solar water heaters. The proposed solar collector utilizes a phase change material namely Octadecane paraffin, with melting temperatures of 28°C which is categorized as non-toxic with long-term chemical stability PCM. As PCMs particularly in powder form may not be effective by itself due to the poor heat transfer rate, low thermal diffusivity and thermal conductivity, by combining CNT layers with the high thermal diffusivity and thermal conductivity compare to phase change materials, we are able to overcome the shortcomings of PCMs and design an innovative and efficient solar water heater. With the current technology, we can provide a near ideal black body surface, absorbing a maximum of 98%, between 600–1100 nm, of solar light striking the surface, and providing additional spectral absorption which improves the performance of the solar heater. Applying CNT sheets in conjunction with PCM enables heat storage directly on the collector for a more constant output, even on a cloudy day and prolonged output of heat at night.

Radiation heat transfer is the dominant model of heat transfer in the large scale industry boiler, especially in oxy-fuel combustion condition. Radiative properties of combustion gases and char oxidation in the oxy-fuel condition are obviously different from the air-fuel combustion, due to the N 2 replaced by CO 2 . Through researchers proposed many helpful correlations based on the air-fuel Weighted-Sum-of-Grey-Gases-Model (WSGGM), the absorption coefficients were commonly constant or correlations were discrete by the classical molar ratio of H 2 O to CO 2 (MR), which were mismatching the continuous value of MR in the real furnace. Meanwhile, the discrete MR is also not applied to the computational fluid dynamics (CFD). In this paper, new correlations for the WSGGM are determined as polynomial function of MR and temperature, which can be conveniently employed in Fluent by the form of user-defined-functions in C language. Parameters of model are fitted by total emittances calculated based on the timely HITEMP 2010 database. New correlations are validated by comparing the emittances with line-by-line calculations and other classical models. New correlations are employed in the CFD for the real industrial oxy-fuel combustion with the temperature range of 400–2600K, pressure path-length between 0.01 and 60 bar m. Several assumed test cases have been investigated to evaluate the accuracy of the models. Modified correlations for WSGGM give a better accuracy of the total emittances for the mixed combustion gases in the real furnace. New models including radiative and chemical reaction mechanisms have been employed to CFD modeling of combustion process for a tangentially fired 300MWe utility boiler. The industrial boiler is modeled by a partition meshing method with the hexahedral structured mesh. Due to the atmosphere shift from N 2 to CO 2 , three aspects are essential to be modified for oxy-fuel: radiation model, char oxidation model and homogeneous volatile oxidation model. To investigate the performance of the furnace, air-fuel combustion selected as the conference, three other cases employed are defined as Oxy21 (vol21%, O 2 ), Oxy26 (vol26, O 2 ) and Oxy29 (vol29%, O 2 ), respectively. Temperature profile and heat transfer are investigated for the different test cases. Meanwhile, the simulation and calculation heat transfer in the furnace are also compared. The results show the new modified simulation has an approximate 4–11% lower than the thermodynamic calculation. To achieve an identical heat flux and temperature distributions with the air-fuel case, the molar fraction 29% of O 2 is essential for the selected implementation. (CSPE)

Simplified sub-models for coal combustion are widely used in CFD simulation of pulverized coal fired boiler. A large-scale boiler was simulated to investigate the effects of some advanced sub-models. Through calculating several cases using different sub-models, it is known that the predicted ignitability of burners is closely related with the generation of H 2 . In the case without taking into account H 2 , the burners show poor ignitability. Using a multi-step mechanism for gas combustion, including char gasification and detailed compositions of volatile largely improve the ignitability of burners. The good ignitability also leads to more heat absorption in boiler and less CO in furnace. CO can be also increased because of the char gasification and detailed compositions of volatiles. Therefore, it is necessary to using multi-step mechanisms for gas combustion, char gasification, and detailed compositions of volatiles to obtain more accurate simulation results.

A hybrid solar water collection system was designed to determine the benefits of combining a flat plate collector with evacuated tubes. The system used a flat plate collector with five evacuated tubes to maximize solar absorption from direct and diffuse solar radiation. The performance of the hybrid collector was evaluated by collecting data while the system operated at a range of flow rates and solar insolation levels over several months. The maximum change in temperature was 48.6°C with a flow rate of 0.0063 kg/s. Analysis of the data quantified the maximum change in temperature and a range of maximum system efficiency between 40–45%.

In the current study, a fully nonlinear two-dimensional numerical wave tank is developed using the commercial CFD software, Ansys Fluent 15.0, in order to study the absorption characteristics of an OWC at linear and highly nonlinear steep waves. The two-phase Volume-Of-Fluid (VOF) method is employed to predict the water free surface evolution. The numerical results are first validated against the available analytical data in the literature. The good agreement between the numerical results and those of analytics, revealed the capability of the developed numerical tank to study the performance of the OWC. Next, the simulations are performed for strongly nonlinear waves, up to the wave steepness of 0.069 ( H/L =0.069), where H is the wave height and L is the wave length. The optimum pneumatic damping of the air turbine at such strongly steep and nonlinear waves is determined. Results show that the absorption efficiency of the OWC decreases considerably as the wave height increases. Moreover, the maximum wave energy absorption efficiency for the highly nonlinear waves occurs at a pneumatic damping coefficient lower than that of the linear theory.

Currently membrane gas absorption (MGA) is a novel approach for gas separation. In the present work, a wide-ranging 2D mathematical model for CO 2 absorption from the N 2 /CO 2 mixture is proposed. Single solvents [H 2 O, ethylenediamine (EDA), diethanolamine (DEA), monoethanolamine (MEA), piperazine (PZ)] and blended solvents [DEA/PZ] were used as the absorbents. The non-wetting mode for the membrane contactor was considered in the calculations. The effects of gas concentration and velocity, and liquid concentration and velocity on CO 2 removal were observed. The simulation results were verified with the experimental data showing a good agreement. The modeling results indicate that gas concentration and velocity have a negative effect on the capture process, while liquid concentration and velocity enhance CO 2 capture. Also, it is noted that PZ has the best absorption performance than other single absorbents. The chemical solvents are much better than the physical solvent for the absorption of CO 2 . For mixed absorbents based on amine solutions, the CO 2 removal efficiency could be about 20% higher than that of the single solutions. Thus, this model could provide the optimum operating conditions for acid gas absorption in the hollow fiber membrane module. It is also proved that the MGA approach exhibits a good potential in power-plant waste gas purification.

Renewable energy resource is considered by many developed and developing countries as a promising and a cost effective candidate to provide energy. The operation of cooling systems in the United Arab Emirates (UAE) have some operating problems especially in summer such as severe grid dependent, excessive energy consumption, high emissions and high costs. So, more economically and environmentally friendly HVAC systems are desired to provide the required electricity demands for cooling loads while saving energy and having low emissions to the environment. In this paper, a parabolic trough solar collector is integrated with a triple effect absorption cooling system for sustainable development. A computer code is developed using Engineering Equation Solver (EES) software to obtain all required thermodynamic properties of water-lithium bromide (H 2 O/LiBr) solution and to optimize all operating parameters and carry out all detailed energy and exergy analyses for a 10 kW cooling capacity. In addition, the parabolic trough solar collector (PTSC) is also designed for the required cooling load and its overall dynamic behavior is also investigated. The solar irradiance available in the UAE on a monthly basis is used in the analysis of a PTSC-based HVAC cooling system. Energetic and exergetic efficiencies of the PTSC for every month are also evaluated under different operating conditions. The Overall monthly energy and exergy efficiencies of the integrated PTSC-based HVAC system for a constant mass flow rate of Therminol-66 and concentration ratio are calculated. The dynamic variation of the coefficient of performance of the integrated system with the solar irradiance and mass flow rate of the oil are also evaluated. Results show that both energetic and exergetic COPs are decreased with increasing the solar irradiance for a constant mass flow rate of oil and constant concentration ratio. It is found that increasing the mass flow rate of the oil from 0.1 to 0.5 kg/s results in decreasing the energetic COP from 2.15 to 1.98 and the exergetic COP from 2.05 to 1.93.

The calculations were performed at different power levels for selected IFBA and non-IFBA NPP Krsko fuel assemblies using 2D lattice codes (DRAGON, NEWT and FA2D) to show quantitative influence of xenon concentration on homogenized cross sections. In addition to usual influence on fast and, to larger extent, on thermal absorption cross sections, similar type of influence is found in case of fission cross sections, and to some extent in fast to thermal removal cross section. Based on relative change of cross sections from the values obtained during reference depletion, burnup and power level dependent correction values were calculated and included in separate cross section library. Limited dependence of correction values on IFBA presence and enrichment is found. When applied within nodal code the correction has potential to improve prediction of multiplication factors (boron concentration) and axial power distribution in Pressurized Water Reactor (PWR) reactors.

The fuel rod performance of enhanced thermal conductivity UO 2 /graphene composites is investigated through a LBLOCA analysis. The benefits increased monotonically with increasing thermal conductivity in terms of reduced fuel center temperature and PCT. The performance of the UO 2 /graphene composite fuel is assessed in OPR-1000 (Optimized Power Reactor-1000) during a LBLOCA. Graphene can be a promising material for developing advanced nuclear fuel because of its property about the high thermal conductivity and low absorption cross section. The results confirm a LBLOCA performance related to PCT of the UO 2 /graphene composite fuel and its potential while maintaining large safety margins.

On a recent project, Sargent & Lundy developed a novel system to dehydrate CO 2 by utilizing heat recovered from the gas compression system and absorption chillers for applications such as Carbon Capture and Sequestration (CCS) projects on fossil fuel-fired power plants. The dehydration system is based upon recovering waste heat from the compression cycle and transferring it to absorption chillers to generate chilled water for dehydration purposes. The chilled water is used within multiple stages of the CO 2 compression train. The system is capable of dehydrating the supercritical CO 2 stream to a level of 29 lbm of H 2 O per mmSCF for transport in a carbon steel pipeline for enhanced oil recovery and sequestration purposes. The process requires the recovery of waste heat, absorption chillers and cooling water from a conventional cooling tower. The system provides a unique option to reduce compression train power requirements and emissions.

Crushable material has widely been used as an engineering solution for energy absorption devices among many industries. Abnormal and severe accident loads in the design of nuclear power plants are required to be addressed in order to comply with Nuclear Regulatory Commission (NRC) requirements which makes the crushable material more suitable in its highly dynamic application. One of the severe loads is from a postulated high energy piping system rupture. Its effects are required to be mitigated so that the proper operation of safety related systems, structures and components (SSC) of these facilities is assured. The postulated pipe rupture loads are among the highest loads that need to be addressed in the design process of nuclear power plants. The impact forces produced by the postulated pipe rupture are typically being absorbed by energy absorption devices called “Pipe Whip Restraints” in which the restraints can minimize the loads affecting the SSCs to within an acceptable limit. This paper provides a simplified closed-form solution to determine the energy absorbing characteristic that will help to design these devices. This paper will also provide a comparison between results of the proposed simplified closed-form solution equations to the experimental test results and the calculated results using finite element analysis.

Two of the most common methods currently being employed for combustion turbine inlet air temperature control are evaporative cooling and mechanical chilling. The former requires significant quantities of water, while the latter has a large parasitic power consumption. This article outlines an emerging technology, absorption refrigeration turbine inlet air conditioning (ARCTIC™) that mitigates both of these issues, while offering precise control over inlet air temperatures. Such control is quite important during peak load periods, when every megawatt can be of enormous value to a power producer. Also of significant importance is that operation of combustion turbines at maximum efficiency minimizes the CO 2 footprint of the machines. This aspect has positive implications for power producers wishing to be as green as possible. The ARCTIC process is based on straightforward absorption-refrigeration technology utilizing combustion turbine waste heat, and thus should present the reader with easy-to-understand details.