Preheating System Research Articles

Novel Feedwater Preheating System for Parabolic Trough Solar Power Plant

Novel Feedwater Preheating System for Parabolic Trough Solar Power Plant

Solar Preheating in Power Plants: An Overview Of The Current State Of The Technology

Utilizing preheating units is one of the most critical ways to improve the performance of thermal power plants. Increasing the overall efficiency of Brayton or Rankine cycles by preheating the air or stream may result in considerable increases in output power and efficiency. When it comes to renewable energy, solar energy is an appealing alternative for use as a source of preheating since it is readily accessible. The current article discusses the use of solar energy for preheating air and steam in thermal power plants, as well as other uses. The performance of the systems is being improved, according to evaluations, as a result of a variety of elements, including the configuration of the reference system, the operating environment, the applied technology, and so on. Aside from improving the overall efficiency of the power plant, the incorporation of a solar preheating system may significantly decrease fuel usage and, as a result, carbon dioxide emissions. Furthermore, owing to the unavailability of solar energy during the night and overcast hours, thermal storage units may improve the system's dependability while also increasing the contribution of solar energy to the system's output.

Effect of workpiece preheating on tool wear and delamination at the hole exit in high feed drilling of carbon fiber reinforced plastics with diamond-coated tools

High feed drilling of carbon fiber reinforced plastics (CFRP) poses a risk of serious tool wear and delamination caused by high drilling thrust force despite improving productivity. However, by taking advantage of the proper thermal softening of the epoxy matrix in CFRP, a decrease in forces related to tool wear and delamination is achievable under high feed. Through this study, thermal softening of epoxy matrix by preheating was effective in reducing thrust force and tool wear in the drilling of CFRP with diamond-coated tools. Hole exit delamination factors decreased by adjusting workpiece temperature to the proper value using a developed preheating system under high feed (0.2 mm/rev).

Humidification-Dehumidification Desalination System Powered by Simultaneous Air-Water Solar Heater

A humidification–dehumidification (HDH) desalination system requires thermal energy to desalt seawater. An environmentally friendly approach to obtain thermal energy is to utilize solar energy using solar collectors. Either seawater or air (or both) are typically preheated by HDH desalination systems before these fluids are conveyed to the humidifier column. Compared with preheating only air or water, preheating both is preferred because improved performance and higher productivity are achieved. Many researchers have proposed dual preheated HDH systems utilizing two separate solar heaters/collectors for simultaneous air–seawater preheating. In this study, dual-fluid preheating is achieved using a single solar collector. The proposed simultaneous air–water solar heater (SAWSH) is a modified flat-plate collector designed for simultaneously preheating air and seawater before the fluids reach the humidifier. A thermodynamic study was conducted using formulated mathematical models based on energy and mass conservation principles. Then, the dual-fluid heating HDH system is compared with HDH systems in which only air or only water is heated. This work found that the former outperformed the latter. The daily and monthly performance levels of the system in terms of the outlet temperatures of air and water, distillate rate, and gain output ratio were calculated using the weather data of the hot and humid climate of Jeddah City, Saudi Arabia.

Technology Innovation for the Manual Laser Cladding of High-Alloy Tool Steels

This paper presents the development and successful application of an inductive preheating system running simultaneously with the manual laser cladding process in order to enable the repair of high-alloy tool steels having a highly limited weldability. In this study, the design and optimization of a suitable inductor as well as the analysis of the welding process were carried out by means of FE-simulation in order to generate material deposition without imperfections. Parameter variation studies were conducted while parallel modifying the generator power resulting in different preheating temperatures. These examinations showed that by using appropriate process parameters and an inductive preheating temperature of 200 °C, crack- and pore-free deposition layers could be produced on the commercial high-alloyed PM steel Elmax. This result can be explained by FE-simulation demonstrating that the cooling rate was halved in the weld and in the heat-affected zone. In conclusion, this study shows the high potential of the developed technical innovation for the manual laser cladding of high-performance tools.

A 2E Analysis and Optimization of a Hybrid Solar Humidification-Dehumidification Water Desalination System and Solar Water Heater

This study presents an energy-exergy analysis of a Humidification-Dehumidification (HD) solar water desalination system. The extensive application of the HD system lies in its low energy consumption and ability to exploit solar energy to supply all the heat energy demands. The unsteady governing equations were solved until the system reached a steady state. The simulations were done with the Euler approach to solving the system of energy balance equations numerically. This study's main goal was to investigate the effect of different configurations of the hybrid system and various operating conditions on the performance of the solar HD water desalination system. The optimum configuration was selected based on thermodynamic and exergy analyses. The effects of important parameters such as inlet water and air mass flow rate in the humidifier and dehumidifier water temperature and mass flow rate on the system's operation were studied. This paper also explored the feasibility of the extra heat as a domestic water heater under various conditions. Based on exergy analysis, it is shown that the solar desalination system with air-water preheater with the power of 1057.9 W had the most exergy destruction in comparison with the two other systems (i.e., water preheater system and air preheater system with the respective exergy destructions of 901.3 W and 75.3 W). Comparing the values of freshwater production, exergy destruction, and exergy efficiency, the solar system with a water preheater was selected as the optimum one.

A review on applications of solar energy for preheating in power plants

One of the main approaches for performance improvement of thermal power plants is employing preheating units. Preheating the air or stream in Brayton or Rankine cycles can significantly improve the overall efficiency output power. Solar energy, as an available renewable energy, is an attractive option to be employed as the source of preheating. In the present article, applications of solar energy for preheating air and steam in thermal power plants are reviewed. According to reviews, enhancement in the performance of the systems is under influence of several factors such as the configuration of reference system, operating condition, applied technology etc. Besides performance enhancement of the power plant, integration of solar preheating system can remarkably reduce the fuel consumption and consequently the emission of carbon dioxide. Furthermore, due to the unavailability of the solar energy in nigh and cloudy hours, applying thermal storage units can enhance the reliability of the system and increase contribution of solar energy in the output of the system.

Monitoring of Solar Still Desalination System Using the Internet of Things Technique

In this work, a smart solar still prototype for water desalination is designed. It consists of a basic solar still, a solar preheater and a remote monitoring system based on the Internet of Things (IoT) technique. The monitoring system is developed and integrated into the hybrid solar still in order to control its evolution online, as well the quality of the freshwater provided by checking measured parameters such as pH. Thanks to the IoT technique, parameters collected by the monitoring system (e.g., air temperatures, relative humidity, etc.) are uploaded to the cloud for online remote monitoring. The users are notified by an SMS about the status of the system (e.g., water level in the basin, water in the tank, etc.), using an GSM module. The whole system, including the preheater, water pump, valve, sensors and an electronic board, is powered by a photovoltaic module of 75 Wp. The results showed that by adding a solar preheater system, the evaporation process is accelerated and, consequently, the daily yield is improved and reaches the value of 12.165 L/m2/day. The saline concentration of the tested ground water is 3.9 g/Kg (0.39%), and, after desalination, the salinity is 0.1 g/Kg (0.01%).

Comparison of PMtotal, PM10, PM2.5, NOx, and SO2 Emission Factors from Coal-fired Power Plants per Load Change

For two bituminous coal-fired power plants with 500 MW and pulverized coal combustion type, the concentration of PMtotal, >PM10, PM2.5-10, PM2.5, NOx, and SO2 was measured, and their emission factors were calculated through field measurement. The measurement points started from the boiler downstream and continued to the air pollution control devices (APCDs) that are installed in series, namely, the selected catalytic reduction system (SCR), air preheater (APH), electrostatic precipitator (ESP) and wet flue gas desulfurization system (WFGD). The measurement was performed at one point for more than three times by using the Korean standard method for air pollutants. However, all measurement points, except for the stacks, were not representative of the standard test method. In addition, the PM concentration was too high to reduce the collection time due to isokinetic sampling. There is a limitation of how representative the measurement results can be. During the field measurement period, the power production rate of the two coal-fired power plants was 91.6% and 79.2% in the P-1 and P-2, respectively. Moreover, in the P-2, with a low power production rate, the concentration of PMtotal, PM10, PM2.5, and NOx was found to be low, and the emission factor calculated by dividing the measured concentration value by the fuel usage was also estimated to be low. Such results are due to the coal combustion chamber and various types of APCD being operated at a lower-load condition than the design capacity. In turn, the number of pollutants generated was less, and the removal efficiency of the pollutant became high. However, it was found that the concentration of SO2 generated and the emission factor are more significantly affected by the sulfur content of the coal than the load factor change. To this end, reducing the operation load of the coal-fired power plant improves the combustion efficiency and APCDs performance and decreases the emission factor, resulting in more reduction of the air pollutants than that based on the simple calculation.

Characterization of Sb scaling and fluids in saline geothermal power plants: A case study for Germencik Region (Büyük Menderes Graben, Turkey)

Turkey is located on the seismically active Alpine-Himalayan belt. Although tectonic activity causes seismicity in the Anatolian plate, it also constitutes an important geothermal energy resource. Today, geothermal energy production is heavily concentrated in Turkey's Western Anatolia region. Graben systems in this region are very suitable for geothermal resources. The Büyük Menderes Graben (BMG) is an area of complex geology with active tectonics and high geothermal potential power. Germencik (Aydın) is located in the BMG, where the geothermal waters include mainly Na-Cl-HCO3 water types. This study examined the stibnite scaling formed in the preheater system of the Germencik Geothermal Field (GGF). The formation of the stibnite scaling on the preheater system dramatically reduces the energy harvesting of the GGF. Considering the stibnite scaling in the surface equipment, the optimum reinjection temperature was determined as 95 °C to prevent stibnite scaling in the GGF.

Efficient waste heat recovery system for diesel engines using nano-enhanced phase change materials

Cold start is one of the most difficult combustion phases of a diesel engine; and a large percentage of pollutants are produced during this period. Therefore, the present study focuses on proposing a numerical investigation of a novel design of an air preheating system to warm up the engine intake air at ambient air temperatures of 273 and 268 K. The preheating system consists of nano-enhanced phase change materials (NEPCM) housed in a plate heat exchanger. A comprehensive thermal model was developed and validated using experimental data from the literature. The model couples the transient turbulent fluid flow of the engine exhaust gases with the melting and solidification processes in the NEPCM domain. The effect of nanoparticle type, nanoparticle weight fraction, engine rotational speed, and ambient temperature were investigated. At 2000 rpm, the charging time was reduced by 34.88%, 30.23%, and 25.58% when using 5 w.t% of SiO2, Al2O3, and CuO nanoparticles, respectively. During the discharging process, in less than 1 min, the cold intake air can be heated from ambient temperatures of 273 and 268 K to 301.8 and 300.6 K, respectively.

Experimental investigation of cold start emission using preheating system on the exhaust line at the idle conditions on a spark ignition engine

Experimental investigation of cold start emission using preheating system on the exhaust line at the idle conditions on a spark ignition engine

Combustion of hazelnut shell-lignite blends in poly-particulate beds

In this study, combustion behaviours of blends prepared from 2.18 mm mean size lignite and hazelnut shell particles in specific proportions were investigated using a vertical pre-heated furnace system through which air was flowing upwards by natural convection. The results revealed that the ignition time of the blends approached those of hazelnut shell with temperature and showed certain interactions of the two materials during the volatiles combustion period. Combustion time generally complied with volatiles and carbon combustion rates of the two materials and their blends. Carbon combustion time decreased with temperature and hazelnut ratio, and implied some interactions of the materials. Although any effect of initial furnace temperature and hazelnut ratio of the blends on the NOx emissions was not clearly seen, SO2 emission levels depended on these factors.

Comparatively investigation of real MSW and biomass tar treatment by a rotating gliding arc

Effective tar removal is the bottleneck in gasification application with municipal solid waste (MSW) and biomass as feedstocks. Herein, a rotating gliding arc plasma reactor equipped with a specific designed swirling generator and pre-heating systems is firstly proposed to treat real tar rather than tar surrogates. The composition of MSW and biomass tar is comparatively analyzed. The influence of vapor concentration, CO2 concentration and the discharge current on the destruction efficiency and distribution of gas products are systematically emphasized. The destruction efficiency of major components from both MSW and biomass tar can reach up to over 90%. The order of destruction efficiency of the components tends to be η (Monocyclic species) > η (Bicyclic species) > η (Tricyclic species). Amongst, species with oxygen-containing functional group such as –OH is prone to be destructed compared with those aromatic hydrocarbon species. Similar changing trend of MSW and biomass tar destruction efficiency dependent on operating parameters is detected, with slight differences attributed to the differences of element and group content.

CFD study of a CI engine powered in the dual-fuel mode with syngas and waste vegetable oil

Syngas production from biomass gasification and its use in combined heat and power (CHP) generation systems is a feasible alternative to traditional fuels in Internal Combustion Engines (ICEs), although its quality is poorer in terms of calorific value and energy density. Therefore, a viable option for its exploitation can be assured if ICEs operate in dual-fuel (DF) mode, where employing non-edible oils (as Waste Vegetable Oils, WVO) as a further residual material may solve issues related both to the utilization of diesel fuels and to the high costs for biodiesel production. The practice promotes a virtuous circle to enhance material recovery without disposal. A combined experimental-numerical activity for the analysis of the performances of a Compression Ignition (CI) engine in the DF mode with syngas and WVO is here presented. An appropriate pre-heating system is mounted on the engine injection line to reduce the WVO viscosity. Experimental data collected in terms of in-cylinder pressure cycle, heat release rates and main pollutants at different loads are used to validate a properly developed three-dimensional (3D) Computational Fluid Dynamics (CFD) model, that helps investigating the detail of the syngas fuelling on power output and emissions.

Evaluating the performance of liquid immersing preheating system for Lithium-ion battery pack

Abstract Preheating batteries is crucial to improve the performance and lifetime when using lithium-ion batteries in cold weather conditions. Even though the immersing preheating system (IPS) has demonstrated attracting advantages, there is still lack of systematical evaluation about its performance and factors affecting the performance. To bridge the knowledge gap, this work considered the following key performance indicators: the rate of temperature rise, the temperature uniformity of the cell and the pack and the energy storage density; and the influences of the inlet flow rate and inlet temperature of heat transfer fluid (HTF), the gap between the batteries, the number of the batteries and the location of the HTF inlet and outlet on the preheating performance were investigated. A 3D CFD model was developed, which has been validated against experiments. Based on simulations, it was found that the IPS can achieve a high rate of temperature rise, which is up to 4.18 °C/min, and a small temperature difference in the battery pack, which is less than 4 °C. The number of batteries has been identified to have the biggest impact on the rate of temperature rise and the uniformity of the battery pack. Allocating the inlet on the left/right faces of IPS can effectively reduce both maximum temperature difference of the cell and the pack.

Implementation of Pre-Heating System in Stenters for Improving Machine Performance and Increasing Efficiency

In textile finishing, stenters always draw considerable attention to newer inventions to boost up production via maximum utilization of energy. Prior to main drying or heat-setting chambers, intermediate heating of cylindrical system especially by steam has a direct blessing to moisture evaporation, processing speed, fabric quality and so on. Based on actual operational data, this study reveals the outcomes of a pre-heating module installed within a stenter. After employing the pre-heating system to knit fabrics of different structures and compositions, 23% - 61% moisture reduction was found and the speed of processing fabrics was increased simultaneously by 17% - 30% without any compromise on fabric quality. Moreover, no less than 8.21% savings in annual electricity consumption were observed.

Techno-economic analysis of power generation by turboexpanders in natural gas pressure reduction stations

The objective of this paper is to perform a techno-economic feasibility study of recovering pressure energy of natural gas stream through installing turboexpanders in a pressure reduction station and selling the generated electrical power to the national grid. As a case study, the operating and real conditions of a major pressure reduction station in Iran is collected throughout the years 2015, 2016 and 2017. To account for the effects of the inherently variable operating conditions, a thermodynamic model based on exergy analysis estimates off-design turboexpander isentropic efficiency, size and cost estimate as well as minimum preheating temperature required to avoid hydrate formation due to the expansion process. The detailed economic analysis shows that for the project to be economically feasible, an electricity purchase price of > $0.08/kWh is required. Furthermore, the results of this study are useful for designing automatic preheating temperature control system.

Techno-economic analysis of power generation by turboexpanders in natural gas pressure reduction stations

The objective of this paper is to perform a techno-economic feasibility study of recovering pressure energy of natural gas stream through installing turboexpanders in a pressure reduction station and selling the generated electrical power to the national grid. As a case study, the operating and real conditions of a major pressure reduction station in Iran is collected throughout the years 2015, 2016 and 2017. To account for the effects of the inherently variable operating conditions, a thermodynamic model based on exergy analysis estimates off-design turboexpander isentropic efficiency, size and cost estimate as well as minimum preheating temperature required to avoid hydrate formation due to the expansion process. The detailed economic analysis shows that for the project to be economically feasible, an electricity purchase price of > $0.08/kWh is required. Furthermore, the results of this study are useful for designing automatic preheating temperature control system.

Comparison between the energetic and environmental performance of a combined heat and power unit fueled with diesel and waste vegetable oil: An experimental and numerical study

A combined experimental and numerical characterization of a Compression Ignition (CI) engine is here presented under Diesel and Waste Vegetable Oil (WVO) fueling at different loads. Main objective is to prove the feasibility of preheated WVO as substitute of Diesel fuel in CI engine for cogeneration purposes without modifying the engine geometry. After a characterization of the WVO physical properties, an appropriate pre-heating system is mounted on the engine injection line in order to reduce viscosity. The in-cylinder pressure analysis reveals no significant differences under both fuelling modes, despite an increased fuel consumption measured for WVO. This last provides higher NOx, CO and CO2 emissions, with a strong reduction (50–80%) of the soot amount. The potential impact of employing WVO is then assessed through a Life Cycle Assessment (LCA) methodology with focus on the fuel production and use stages. A reduction in all the major impact categories is noticed with respect to Diesel fueling. At the same time, a 3D CFD model of the engine is developed and validated. The WVO injection process shows slower spray break-up and evaporation rates due to higher viscosity and density. Despite the higher penetration lengths and increased amount of fuel burnt closer to the cylinder walls, the soot at the exhausts remains low as a consequence of the absence of aromatic compounds and an enhanced oxidation process due to the presence of oxygen atoms in the WVO molecules. This aspect is also responsible of the increased NOx release.