Amount Of Heat Research Articles

Investigation on heat recovery strategies from low temperature food processing plants: Energy analysis and system comparison

Industrial food processing plants often have significant thermal requirements at both low and high temperatures. These plants can produce a variety of products including frozen, chilled and grilled/steamed foodstuff, creating thermal demands at several temperature levels. Rapid freezing of the foodstuff at temperatures below -40 °C is required to preserve a high-quality product while steaming/grilling of foodstuff require heat above 100 °C. Heat recovery from the low-temperature refrigeration system provides an interesting opportunity to reduce the overall energy consumption of the plant. This paper presents different strategies to achieve heat recovery from a CO2/NH3 cascade refrigeration system. The low stage of the cascade features pumpcirculated CO2 circuits at -40 °C and -5 °C evaporation levels, while the high temperature stage consists of an ammonia circuit. For this investigation, a case is defined based on requirements for temperature level and heat quantity from the industry. Subsequently, different strategies for the integration and control of the energy systems are examined. Finally, the strategies are compared with selected key parameters and the results are presented. This article is a translation of the article by Ahrens MU, Selvnes H, Henke L, Bantle M, Hafner A. Investigation on heat recovery strategies from low temperature food processing plants: Energy analysis and system comparison. In: Proceedings of the 9th IIR Conference on the Ammonia and CO2 Refrigeration Technologies. Ohrid: IIF/IIR, 2021. DOI: 10.18462/iir.nh3-co2.2021.0034 Published with the permission of the copyright holder.

Design and Fabrication of a Novel Commercial Baking Oven

This study presents the design and fabrication of a novel wood-fired commercial oven for baking bread. The oven design features an external combustion chamber with heating elements which comprise stainless-steel pipes filled with magnesia starting from the combustion chamber to the 3 oven compartments. Each compartment has 12 heating elements laid under a mild steel sheet metal where the dough mould and its content is placed. Heat loss due to conduction, radiation and convection was prevented by the use of a double wall in both oven and combustion chamber compartments with silica brick and fibre glass respectively, and the oven was fired with wood to bake some dough. Findings showed that maximum temperature attainable by the oven was 700°C, however, the temperature required for baking bread is between 150°C and 180°C and the time was 25 minutes, the quantity of heat generated per time using 10 kg of wood was about 15,088 KJ. Furthermore, the physical appearance of the products was examined to meet consumers’ requirement and a total of 400 bread of 180 mm × 120 mm × 80 mm dimensions can be baked at a time. With slight modifications in the oven design, this number can be improved. The oven can be fired with other types of solid biofuels and can be used for metallurgical furnace applications like annealing, tempering and other heat treatments of metals.

Signature of the western boundary currents in local climate variability.

The western boundary currents are characterized by narrow, intense ocean jets and are among the most energetic phenomena in the world ocean. The importance of the western boundary currents to the mean climate is well established: they transport vast quantities of heat from the subtropics to the midlatitudes1, and they govern the structure of the climatological mean surface winds2-6, precipitation4-6 and extratropical storm tracks7-13. Their importance to climate variability is much less clear, as the tropospheric response to extratropical sea surface temperature (SST) variability is generally modest relative to the internal variability in the midlatitude atmosphere12-14. Here we exploit novel local analyses based on high-spatial-resolution data to demonstrate that SST variability in the western boundary currents has a more robust signature in climate variability than has been indicated in previous work. Our results indicate that warm SST anomalies in the major boundary currents of both hemispheres are associated with a distinct signature of locally enhanced precipitation and rising motion anomalies that extend throughout the depth of the troposphere. The tropospheric signature closely mirrors that of ocean dynamical processes in the boundary currents. Thus, the findings indicate a distinct and robust pathway through which extratropical ocean dynamical processes influence local climate variability. The observational relationships are also reproducible in Earth system model simulations but only when the simulations are run at high spatial resolution.

Analysis of heat transfer modes in the cooling of blocks generating different heat quantities

Achieving improved cooling efficiency and control in electronic components with varying heat outputs can be realized through a thorough analysis of different heat transfer modes, focusing on their contributions and interactions within the system. The analysis is conducted within a cavity containing three circular blocks generating varying amounts of heat. The blocks are affixed to an insulated plate, dividing the cavity into two identical sections with different fluids and different cooling mechanisms. In the open portion of the divided cavity, block cooling is achieved through forced convection using a nanofluid, while the closed section dissipates heat through natural convection and surface radiation. The numerical solution of the governing equations is performed using Galerkin's Finite Element Method, with detailed examination of the cooling process considering various parameters, such as block displacement (1.5cm≤y1≤3.25cm) and dimensions (0.25cm≤R≤1.5cm), Reynolds number (10≤Re≤1000), nanoparticles nature and volumetric fraction(0 %–10 %), emissivity (0≤ε≤1), thermal heat ratio(0.125 to 8), and cavity inclination angle(0°–180°). The results show that the combination of natural convection and surface radiation can be highly effective, rivaling forced convection in cooling the blocks. The study shows that an increase in the Reynolds number results in a temperature reduction of up to 6 °C, while increasing the emissivity leads to a more significant drop of around 10 °C. Additionally, miniaturizing the blocks by reducing their radius by a factor of six causes the maximum temperature to rise by over 20 °C.

DC current sensor based upon a fused fiber optic Fabry-Perot interferometer (FPI) and copper wire

In order to meet the demand for direct current (DC) current measurements in industrial production, a new type of fiber optic DC current sensor, combining thin copper wire and fiber optic Fabry-Perot interferometer (FPI), is reported. FPI is a sandwich structure formed by splicing a single-mode fiber (SMF) and a quartz capillary, with a cavity length of approximately 200 μm. The copper wire, with a length of 3.2 cm and a diameter of 1 mm, is attached to the FPI to form the sensor. Due to the excellent thermal conductivity of copper, the results showed that the sensor increased the sensitivity from 4.1 pm/°C to 11 pm/°C. After applying direct current to the sensor, a large quantity of heat generated by the copper wire was absorbed by the FPI, resulting in a significant shift in the resonant wavelength of FPI, which can indirectly measure the current. Three current experiments were performed, and parabolic curves have been used in fitting of the Dip wavelength and the square of the current. The results provide high correlation coefficients with values exceeding 0.99. Therefore, this curve may be used to measure the square of the current, further obtaining the current. In summary, the sensor is compact and durable, easy to manufacture, and provides high correlation coefficients, providing an alternative for measuring DC current.

Heating patterns and temperature distribution of projectile surface in lunar regolith penetration

During penetration, a large quantity of friction-induced heat is generated, significantly increasing the projectile surface temperature. Considering that the temperature variation depends on the physical properties of the target being penetrated, understanding this relationship can aid in extraterrestrial material behavior for detection and analysis efforts. The study investigated the patterns of heat generation and the distribution of temperature on the surface of a projectile as it penetrates lunar regolith. For discrete medium penetration, large deviations appear in temperature prediction due to particle extrusion flow. Thus, a heat flux density model on the projectile surface by introducing a relative velocity factor (RVF) for correction was established. The particle flow characteristics simulation and fitting model of the introduced factor were also obtained. We constructed a theoretical relationship between the resistance and stress model parameters using dynamic modeling. Experimental projectiles recording penetration acceleration and temperature at the points of interest on the projectile surface were designed and tested to obtain recorded data. The temperature field in this process was simulated in COMSOL software to calculate the projectile surface's heat flux density and temperature distribution. The results indicate that the developed model is effective. This research infers the physical characteristics of the penetrating target under specified penetration conditions and provides more dimensional information for lunar regolith exploration.

THE DYNAMICAL INVESTIGATION OF HEAT TRANSFER AND TEMPERATURE CHANGES OF THE SHELL AND TUBE HEAT EXCHANGER USING THE LYAPUNOV METHODS

The dynamic of the heat transfer analysis constitutes an important factor that has drawn the attention of many researchers. Heat transfer is evaluated by considering the heat transfer coefficient, the surface area, and the temperature difference between the surface and the surrounding fluid. The computation of the temperature difference across various surface areas shows that increased heat transfer enhances the proportion of the heat conduction rate. In most cases, the system becomes unstable because inappropriate structural elements and outside disturbances, like ambient temperature can readily change the yielding temperature. As a result, the heat exchanger's efficiency needs improvement. A numerical simulation analyzing the performance of a shell and tube heat exchanger indicates that an increase in the surface area leads to a corresponding increase in the heat transfer rate. To optimize system performance, mathematical models were employed for the stability analysis of temperature changes. MATLAB simulations computed temperature differences in quantities of heat and area, thereby obtaining valuable insights for improving heat exchanger design and operation.

Supercritical retrograde solubility in R-14 and the second law of thermodynamics

A closed transcritical power cycle is described that uses a positive excess enthalpy of solution reaction differential between the reaction in the cycle’s high-density liquid state and low-density expanded gas state to internally transfer heat energy. The heat energy input to satisfy the solution reaction near the cycle’s low temperature is returned as heat during supercritical retrograde solubility near the cycle’s high temperature before that heat energy affects gas expansion. The power cycle format is used to frame this heat energy transfer so that Carnot efficiency can be used to calculate the maximum second law allowed amount of heat energy that can be transferred. If the amount of heat transfer exceeds the determined minimum threshold, the cycle’s Q efficiency will surpass the cycle’s T efficiency. The process demonstrates that the maximum positive excess enthalpy differential allowed by the second law is irreconcilably low.

A MODEL OF ECOLOGICAL CHARCOAL PRODUCTION THROUGH HERBACEAOUS PLANTS IN THE URBAN COMMUNE OF NZEREKORE, REPUBLIC OF GUINEA

The world is confronted to various environmental problems caused by anthropogenic activities, mainly deforestation. This is why promoting the use of herbaceous plants in charcoal production will contribute to the fight against deforestation. In this paper we propose a simple model for producing ecological charcoal using herbaceous plants. The choice of the herbaceous species, the collection, weighing, drying, carbonization, crushing, sieving, kneading, compacting and drying of the briquettes are the different process which allowed us to produce this ecological charcoal based on herbaceous plants. 180kg of soaked weight of herbaceous gave us 90kg of dry weight, carbonized and crushed we obtained 8kg of powder and 1 kg of residue. These 8 kg of herbaceous powder allowed us to produce 156 briquettes of charcoal. A comparison of the physicochemical parameters of our ecological charcoal was made with the charcoal consumed in the urban commune of Nzerekore (wood charcoal). The Results showed that our produced charcoal model releases heat more slowly than wood charcoal, heats up more slowly than wood charcoal and its maximum temperature and heat quantity are higher than that of wood charcoal. The maximum temperature (98.9°C) is reached at 20 minutes for ecological charcoal (charcoal from herbaceous plants) and 97.9°C at 10 minutes for wood charcoal.

Exploration of linear and exponential heat source/sink with the significance of thermophoretic particle deposition on ZnO-SAE50 nano lubricant flow past a curved surface

The present research focuses on exploring the impact of linear and exponential heat source/sink on double-diffusive MHD convective flow heat and mass transport of ZnO – SAE50 nano lubricants in an exponentially stretching curved sheet along with the effect of thermophoretic particle deposition. The heat transmission is considered to be caused by both radiation and convection. The mathematical modelling of the considered problem results in a coupled system of partial differential equations, using suitable similarity transformation variables these equations are reduced to a coupled non-linear system of ordinary differential equations and are solved numerically by adopting the finite difference method to obtain the solution for the field variables. The quantity and spatial distribution of linear heat sources/sinks affect the physical dynamics and optimum status of the entire system and the application of exponential heat sources/sinks can improve heat dispersion and energy efficiency in industrial operations such as nuclear reactors and steel production. The thermophoretic particle deposition parameter controls particle concentration by allowing particles to accumulate on surfaces or in specific areas of the fluid. A rise in Hartmann number causes a mechanical damping force to act in the opposite direction of the fluid motion, lowering the speed of the fluid in the curved sheet. The heat and mass transmission properties are analyzed through the Levenberg – Marquardt backpropagating algorithm and the correlation coefficient has ideal values of unity for training, validation, testing, and overall. In light of this, the anticipated behaviour of the LMNN-BPA indicated that the heat transfer profile numerical data and the network output are in good consensus.

Boosting room-temperature electrocaloric performance in B-site complex antiferroelectrics: A synergistic design approach

As an emerging eco-friendly solid-state refrigeration technology boasting high energy conversion efficiency, there is a pressing demand for ferroelectrics exhibiting significant electrocaloric effect (ECE) at room temperature (RT) for refrigeration applications. In this study, guided by phase-field simulation, we explore the potential of B-site complex Pb[Mg(1–x)ZnxW]1/2O3 (PMZW100x) antiferroelectrics (AFE) to deliver promising symmetric positive and negative ECE near ambient temperature. The first-order AFE-paraelectric (PE) phase transition occurring around 50 °C induces a substantial change in heat quantity and yields prominent ECE upon electric excitation. Maxwell characterization reveals a potential combination of positive and negative ECE, showcasing significant advantages in cooling capacity. Given the technical limitations of existing direct methods for testing under elevated electric fields, low-field ECE is validated using the heat flux approach to ensure the legitimacy of results. Direct measurements demonstrate a high positive ΔT value of 2.76 K at 52 °C and a negative ΔT of –2.91 K at 44 °C (under 140 kV cm–1), surpassing traditional PbZrO3 bulk materials. The coexistence of substantial positive and negative ΔT near RT in PMZW100x offers a new avenue for developing highly efficient solid-state cooling devices.

Modeling the Role of Courtyards with Clusters of Buildings in Enhancing Sustainable Housing Designs

As urbanization increases, buildings require greater amounts of energy for heating and cooling, thereby necessitating the search for effective solutions. The courtyard is often considered a viable option; however, the limited availability and high cost of land resulting from rapid urbanization hinder its widespread use. Consequently, a courtyard with a cluster of buildings is proposed as a feasible solution to address land scarcity. Nonetheless, further investigation is required to effectively integrate this solution into neighborhood urban planning. This study examines the influence of three variables—courtyard orientation, courtyard size, and the arrangement of buildings around the courtyard—on the provision of cooling and heating for buildings. The research focuses on 216 experimental scenarios simulated using Revit software, which excels in its ability to accurately interpret input data and conduct real-time analysis depending on the variables of the building design. The results were recorded for the facades and ground, and the shaded area was computed for each scenario; following these measurements, the shadow areas on both the facade and ground were converted into percentages. The testing involved a group of buildings surrounding courtyards of four different shapes (square, rectangle, triangle, and circle). This approach aimed to identify the most efficient design for implementation in neighborhood planning contexts. The findings indicate that the shape of the courtyard significantly impacts cooling and heating of buildings. Specifically, the square courtyard is unsuitable for countries with Mediterranean climates, such as Jordan, as it can reduce shade coverage by 30%, leading to higher temperatures. Conversely, employing a rectangular courtyard results in a higher proportion of shadows compared to other shapes. The study further demonstrates the influence of the examined variables on the efficacy of the courtyard in cooling and heating of buildings.

Techno-economic evaluation of waste heat recovery from an off-grid alkaline water electrolyzer plant and its application in a district heating network in Finland

The expected extensive production of hydrogen through water electrolysis will generate a substantial quantity of industrial waste heat. Waste heat recovery from electrolyzer facilities would provide significant potential for renewable heat generation into district heating (DH) networks.This paper investigates the techno-economic potential for recovering waste heat from an off-grid alkaline water electrolyzer (AWE) plant and using the heat in a DH network under Nordic conditions. A waste heat recovery system that includes heat pumps, a pit thermal energy storage (PTES) and an electric boiler is modeled and component capacities are cost-optimized for four different scenarios with varying DH demand coverage rates. The waste heat generation of the AWE plant and the DH demand are based on measurements conducted in southeastern Finland.It was found that even with 100% DH demand coverage rate, the levelized cost of heat (LCOH) would be 44€/MWh. Heat pumps constitute the largest single cost while the share of the PTES in the LCOH varies between 11% and 19%. The results were compared with the estimated renewable hydrogen production capacity of Finland, leading to the conclusion that by 2040, there could be potential to fulfill the DH demand of the entire country.

A novel fluorescent material K3NbOF6: Mn4+ for light-emitting diode devices

A series of K3Nb1-xOF6:xMn4+ fluorescent materials were prepared by the cation exchange method. Phase structure, morphology, emission, excitation spectrum and LED packaging of fluorescent materials were tested. The fluorescent material particles are micron-sized (5 μm–20 μm) and have a micro-rod morphology. It has two absorption bands, with the blue light region (∼468 nm) being stronger than the ultraviolet region (∼370 nm). Under the excitation of 468 nm, it shows good narrowband emission in the red light region, mainly with anti-stokes v6 (∼627 nm), which is caused by the double barrier of the 2Eg→4A2g transition broken by the coupling effect of electron and phonon. The optimum doping concentration was 9.1 %, and as the concentration increased again, the dipole–dipole interaction between Mn4+ resulted in concentration quenching. When the fluorescent material operates at high temperature (150 ℃), the emission intensity drops to 50.2 % of which at room temperature. At high temperature, the electrons absorb a large amount of heat energy, and the non-radiation transition to 4A2g energy level causes the thermal quenching effect. In addition, the sample also showed good water stability, after 1 h of hydrolysis, the luminescence intensity decreased to 85.6 % of the initial value. The use of LED packaging with fluorescent materials and InGaN-YAG:Ce3+ can effectively reduce the color temperature of LED from 6856 K to 3745 K, and enhance the Color index from 61.5 % to 76.8 %. Which has great potential for development in the fields of plant growth and backlight display technology.

High adsorption of Cu(II) in novel thiacalix[4]arene/acrylic polymer/diatomite fast fabricated by electron beam irradiation: Controllable microstructures, adsorption performance and mechanism

Chemical grafting of calix[4]arene is a common method to prepare high-performance calix[4]arene adsorbents for heavy metals, however, the chemical grafting process consumes much time and a large amount of heating energy due to the tedious steps. Herein, a thiacalix[4]arene/acrylic polymer/diatomite (TC4A/PAA/diatomite) adsorbent was fast fabricated by electron beam irradiation induced grafting, polymerization and crosslinking technique only in one-pot for the removal of Cu(II) as an important form of heavy metal pollution. Characterization by Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), diffuse reflectance UV–visible spectra and positron annihilation lifetime spectra (PALS) disclosed that the eco-friendly and low-cost TC4A/PAA/diatomite irradiated at 90 kGy namely TC4A/PAA/diatomite (90 kGy) with strong complexing ability owing to many functional groups such as carboxyl, hydroxyl etc in it. The effects of electron beam irradiation dose, initial solution pH, and initial concentration of Cu(II) on the adsorption performance of TC4A/PAA/diatomite were investigated. The isotherm adsorption data of Cu(II) in TC4A/PAA/diatomite (90 kGy) are more suitable for the Langmuir model with the maximum adsorption capacity of 123.30 mg/g. In addition, the bifunctional TC4A/PAA/diatomite (90 k Gy) can efficiently remove Cu(II) and display excellent reusability properties. The adsorption mechanism was further analyzed by FTIR, SEM, X-ray photoelelctron spectroscopy (XPS), diffuse reflectance UV–visible spectra and PALS. This study provides a fast, efficient and eco-friendly synthesis method of calix[4]arene adsorbent, conducing to the design of material innovation. Meanwhile, TC4A/PAA/diatomite (90 kGy) has potential application prospects in the treatment of practical Cu(II) contaminated wastewater.

Plug Flow Reactor (PFR) Design for the Production of 100,000 tons per year of Cumene from the Catalytic Alkylation of Propylene and Benzene

In a bid to meet the ever-growing global demand for cumene based on its wide range of industrial applications and economic importance, the research considered the design of a plug-flow reactor (PFR) for the production of 100,000 tons of cumene per year from the catalytic alkylation of propylene and benzene. The PFR design models were developed by performing the mass and energy balance over the reactor at steady-state operation. The steady-state PFR performance models were simulated using the MATLAB R2023a version at an initial feed and operating temperature of 481.10 K and 483 K with varying fractional conversions from 0 to 0.95 at 0.05 intervals. At a maximum fractional conversion of 0.95, the PFR design specification for volume, height, diameter, space time, space velocity, quantity of heat generated, and quantity of heat generated per unit volume of the reactor was 19.7707 m3, 4.6523 m, 2.3261 m, 3.8766 s, 0.2580 s-1, 1.8035 J/s, and 0.03448 J/sm3, respectively. The profile behavior of the PFR functional parameters at changes in fractional conversion is in agreement with the trend for PFR operation at steady-state conditions, as shown in Figures 2–10. The evaluation of the PFR yearly production dependent on the reactor volume stood at $2,049.838. The article has shown that PFR is a suitable reaction medium for the catalytic alkylation process for optimum production of cumene and sustainability.

Examination of Operational Methods for a Low-Temperature Aquifer Thermal Storage Air Conditioning System Based on Operational Performance and Considerations of Thermal Storage and Pumping Volume Balance

Aquifer Thermal Energy Storage (ATES) systems are garnering attention as high-efficiency air conditioning technologies that contribute to the realization of a carbon-neutral society. This study focuses on an ATES system constructed in Japan, characterized by its complex geological conditions and thin aquifer layers. Detailed actual performance data measured over four years are presented, and performance analysis results show that a COP of 5 was achieved for the overall building cooling and heating system. In addition, the study provides a detailed analysis of the imbalance in heat quantity, remaining heat storage, and other factors based on actual data, identifying operational issues and summarizing specific improvement measures. Finally, as a proposal for a sustainable operational method to balance the cumulative heat storage and pumping volume of cold and hot water, specific operational procedures are summarized, including setting the return water temperature for the next season based on the dimensionless average pumping temperature of the previous season, and a flowchart is presented. There is no prior research that shows such specific operational procedures, and this can be considered an important achievement of this study.

Analysis of reducing thermal resistance between the PCM and ambient air for improving the power generation characteristics of PCM-based thermoelectric power generators

A power generator comprising a thermoelectric device (TED) and a phase change material (PCM) allows energy harvesting from ambient temperature variations, which exist ubiquitously; thus, such a device has received considerable attention as an energy harvester that can operate at any location. We developed a model for estimating the characteristics of a power generator in ambient air, whose temperature is forcibly changed between two temperature values, such as when an air conditioner is turned on and off. We calculated the influence of latent heat and thermal conductivity of the PCM on the characteristics of power generators with various thermal resistances between the TED/PCM interface and ambient air. Latent heat and thermal conductivity of the PCM affect the amount of heat energy (Q) transfer between the ambient air and PCM and the energy conversion efficiency (ηE), respectively, where the amount of electric energy is given by Q × ηE. The increase in Q caused by an increase in the latent heat of the PCM was almost independent of the thermal resistance between the TED/PCM interface and air. However, the increase in ηE caused by an increase in the thermal conductivity of the PCM decreased as the thermal resistance between the TED/PCM interface and air increased. These results indicate that the techniques to improve the power generation characteristics by increasing the thermal conductivity of PCM, which have been frequently investigated in recent years, are effective only when the thermal resistance between the TED/PCM interface and ambient air is small.

Performance study of low temperature air heated rock bed thermal energy storage system

AbstractOne of the primary types of sensible heat storage systems in drying applications is the packed rock bed. However, to create large‐scale heat storage systems for industrial use, one must comprehend the hydrodynamic and effectiveness of the heat transport mechanism inside the bed. In this study, the thermal storage unit uses river rock as heat storage materials with equivalent particle diameters of 36 mm in bed 1 and 56 mm in bed 2. The rocks were stacked in a truncated cone‐shaped concrete wall section with an average diameter and depth of 1.1 m and 1.3 m, respectively and a volume of 2.32 m3. During the charging phase, two airflow configurations were used, one from the top with an air mass flow rate of 0.753 and 0.332 kg/m2‐s and the other from the bottom with an air mass flow rate of 0.955 kg/m2‐s. During the discharging phase, the entire flow configuration is from the bottom section. It was observed that the mass flow rate and particle equivalent diameter had an important effect on the thermal performance and behaviour of the rock bed during charging and discharging operations. Maximum efficiency was achieved with an airflow configuration provided from the bottom when charging at 0.955 kg/m2.s. Consequently, a sizable quantity of heat or energy (60 MJ) was retained. It was also observed that the relationship between air mass flow rate and particle size was significant, with smaller particles retaining more energy. When comparing bed 1 with bed 2 at this air mass flow rate, bed 1 stored 2.1 times more energy than bed 2. A wind tunnel experiment was used to measure the pressure drop in the packed rock bed. The pressure drop in the bed increases with an increase in particle Reynolds number and decreases with an increase in particle size. Rock bed heat transfer coefficient and Nusselt number were calculated using the correlation that has already been established in the literature smaller particles showed higher heat transfer coefficients and lower Nusselt numbers. This is due to the increase in particle‐to‐particle interaction and larger particle surface areas. For a given Reynolds number, the Nusselt number increases with the size of the rock particle.

Sensitivity and sustainability analysis of combined cycle plant with integrated LNG pressure energy recovery

Although combined cycle power plants (CCPPs) and liquefied natural gas (LNG) have arisen as solutions to the intermittent nature of renewable energy sources, they still need creative methods for performance enhancement and sustainability of the energy systems. Moreover, the energy efficiency of CCPPs is negatively impacted by environmental conditions, higher specific fuel consumption and a large quantity of waste heat released into the ambient. On the other hand, using seawater as a heating medium in LNG regasification circuits has a detrimental effect on the marine ecosystem. In this context, the LNG pressure energy recovery system through a direct expansion cycle (DEC) integrated with CCPP is proposed to improve sustainability, enhance exergetic performance and to reduce the heat recovery steam generator (HRSG) exhaust loss. To improve the cycle performance, low grade heat harnessed from CCPP is used as the heat source in the DEC rather than seawater. The system performance is analyzed by the energy and exergy method through a mathematical model. Moreover, the sensitivity analysis of the combined system is accomplished to examine the influence of LNG flow rate and ambient temperature on various performance indicators of the total system. It is observed that the integration of DEC boosts the HRSG performance by reducing the stack exergy loss and the efficiency is sensitive to LNG flow rate. The total integrated system energy efficiency ηtot, enhanced to 1.55% compared to the base case. Whereas, for ambient temperature in range of 15 – 45 °C, the system minimum and maximum exergetic efficiency ηex,tot is found to be 54.52 % and 55.94 %. Furthermore, the comparison of exergetic sustainability indicators is calculated and presented for three different simulation cases. The results demonstrate that increase in ηex,tot, affects the environment impact factor, ref and the sustainability index, θsi and improved 2.09 % compared to base case combined cycle.