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Records with Subject: Process Design
Showing records 1 to 25 of 117. [First] Page: 1 2 3 4 5 Last
Comparison of a Novel Organic-Fluid Thermofluidic Heat Converter and an Organic Rankine Cycle Heat Engine
Christoph J.W. Kirmse, Oyeniyi A. Oyewunmi, Andrew J. Haslam, Christos N. Markides
December 3, 2018 (v1)
Keywords: combined heat and power (CHP), economic comparison, low-grade heat, non-linear, off-grid power generation, organic Rankine cycle (ORC), performance analysis, thermofluidic oscillator, two-phase, unsteady
The Up-THERM heat converter is an unsteady, two-phase thermofluidic oscillator that employs an organic working fluid, which is currently being considered as a prime-mover in small- to medium-scale combined heat and power (CHP) applications. In this paper, the Up-THERM heat converter is compared to a basic (sub-critical, non-regenerative) organic Rankine cycle (ORC) heat engine with respect to their power outputs, thermal efficiencies and exergy efficiencies, as well as their capital and specific costs. The study focuses on a pre-specified Up-THERM design in a selected application, a heat-source temperature range from 210 °C to 500 °C and five different working fluids (three n-alkanes and two refrigerants). A modeling methodology is developed that allows the above thermo-economic performance indicators to be estimated for the two power-generation systems. For the chosen applications, the power output of the ORC engine is generally higher than that of the Up-THERM heat converter. However... [more]
Cost Engineering Techniques and Their Applicability for Cost Estimation of Organic Rankine Cycle Systems
Sanne Lemmens
December 3, 2018 (v1)
Keywords: case study, cost estimate, heat recovery, investment costs, organic Rankine cycle (ORC)
The potential of organic Rankine cycle (ORC) systems is acknowledged by both considerable research and development efforts and an increasing number of applications. Most research aims at improving ORC systems through technical performance optimization of various cycle architectures and working fluids. The assessment and optimization of technical feasibility is at the core of ORC development. Nonetheless, economic feasibility is often decisive when it comes down to considering practical instalments, and therefore an increasing number of publications include an estimate of the costs of the designed ORC system. Various methods are used to estimate ORC costs but the resulting values are rarely discussed with respect to accuracy and validity. The aim of this paper is to provide insight into the methods used to estimate these costs and open the discussion about the interpretation of these results. A review of cost engineering practices shows there has been a long tradition of industrial cost... [more]
Energy Converter with Inside Two, Three, and Five Connected H₂/Air Swirling Combustor Chambers: Solar and Combustion Mode Investigations
Angelo Minotti
November 28, 2018 (v1)
Keywords: Computational Fluid Dynamics, detailed chemistry, fluid-structure interaction, hydrogen-air combustion, meso-combustor, whirl flow
This work reports the performance of an energy converter characterized by an emitting parallelepiped element with inside two, three, or five swirling connected combustion chambers. In particular, the idea is to adopt the heat released by H₂/air combustion, occurring in the connected swirling chambers, to heat up the emitting surfaces of the thermally-conductive emitting parallelepiped brick. The final goal consists in obtaining the highest emitting surface temperature and the highest power delivered to the ambient environment, with the simultaneous fulfillment of four design constraints: dimension of the emitting surface fixed to 30 × 30 mm², solar mode thermal efficiency greater than 20%, emitting surface peak temperature T > 1000 K, and its relative ∆T < 100 K in the combustion mode operation. The connected swirling meso-combustion chambers, inside the converter, differ only in their diameters. Combustion simulations are carried out adopting 500 W of injected chemical power, stoichio... [more]
NMOS-Based Integrated Modular Bypass for Use in Solar Systems (NIMBUS): Intelligent Bypass for Reducing Partial Shading Power Loss in Solar Panel Applications
Pieter Bauwens, Jan Doutreloigne
November 28, 2018 (v1)
Keywords: diode bypass, partial shading, photovoltaic power, power loss, smart bypass
NMOS-based Integrated Modular Bypass for Use in Solar systems (NIMBUS) is designed as a replacement for the traditional bypass diode, used in common solar panels. Because of the series connection between the individual solar cells, the power output of a photovoltaic (PV) panel will drop disproportionally under partial shading. Currently, this is solved by dividing the PV panel into substrings, each with a diode bypass placed in parallel. This allows an alternative current path. However, the diodes still have a significant voltage drop (about 350 mV), and due to the fairly large currents in a panel, the diodes are dissipating power that we would rather see at the output of the panel. The NIMBUS chip, being a low-voltage-drop switch, aims to replace these diodes and, thus, reduce that power loss. NIMBUS is a smart bypass: a completely stand-alone system that detects the failing of one or more cells and activates when necessary. It is designed for a 100-mV voltage drop under a 5-A load cu... [more]
Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System
Oyeniyi A. Oyewunmi, Christos N. Markides
November 28, 2018 (v1)
Keywords: heat transfer coefficients, low-grade heat, low-pressure expanders, multi-objective optimization, ORC capital costs, organic Rankine cycles (ORC), thermo-economic analysis, working-fluid mixtures
In the present paper, we consider the employment of working-fluid mixtures in organic Rankine cycle (ORC) systems with respect to thermodynamic and heat-transfer performance, component sizing and capital costs. The selected working-fluid mixtures promise reduced exergy losses due to their non-isothermal phase-change behaviour, and thus improved cycle efficiencies and power outputs over their respective pure-fluid components. A multi-objective cost-power optimization of a specific low-temperature ORC system (operating with geothermal water at 98 °C) reveals that the use of working-fluid-mixtures does indeed show a thermodynamic improvement over the pure-fluids. At the same time, heat transfer and cost analyses, however, suggest that it also requires larger evaporators, condensers and expanders; thus, the resulting ORC systems are also associated with higher costs. In particular, 50% n-pentane + 50% n-hexane and 60% R-245fa + 40% R-227ea mixtures lead to the thermodynamically optimal cyc... [more]
Optimization of Internal Cooling Fins for Metal Hydride Reactors
Vamsi Krishna Kukkapalli, Sunwoo Kim
November 28, 2018 (v1)
Keywords: exothermic hydriding reaction, finned surface, hydrogen storage, metal hydride reactor
Metal hydride alloys are considered as a promising alternative to conventional hydrogen storage cylinders and mechanical hydrogen compressors. Compared to storing in a classic gas tank, metal hydride alloys can store hydrogen at nearly room pressure and use less volume to store the same amount of hydrogen. However, this hydrogen storage method necessitates an effective way to reject the heat released from the exothermic hydriding reaction. In this paper, a finned conductive insert is adopted to improve the heat transfer in the cylindrical reactor. The fins collect the heat that is volumetrically generated in LaNi₅ metal hydride alloys and deliver it to the channel located in the center, through which a refrigerant flows. A multiple-physics modeling is performed to analyze the transient heat and mass transfer during the hydrogen absorption process. Fin design is made to identify the optimum shape of the finned insert for the best heat rejection. For the shape optimization, use of a pred... [more]
Design and Optimization of the Slide Guide System of Hydraulic Press Based on Energy Loss Analysis
Mengdi Gao, Haihong Huang, Zhifeng Liu, Xinyu Li, John W. Sutherland
November 28, 2018 (v1)
Keywords: design optimization, eccentric loads, energy loss, hydraulic press, stiffness
The clearances in the slide guide system of a hydraulic press are one of the significant factors affecting its accuracy. These clearances also affect the energy consumption of the press. An energy loss model that considers the oil leaks and friction associated with these clearances was proposed, and the size of clearances was optimized based on the model. The maximum allowable eccentric load and the energy loss on the wedge clearance condition were calculated to ensure the slide and guide pillars function properly. The stiffness of pillars and wear of guide rails were checked under an eccentric load condition. A case for rapid sheet metal forming with a 20 MN hydraulic press was examined. For this case, the optimum fit clearances were found to be approximately 0.4 mm. The energy loss under an eccentric load condition was increased by approximately 83% compared to a non-eccentric load condition. The pillars were optimized by reducing excessive stiffness, which served to decrease the pi... [more]
Performance Evaluation of a Helical Coil Heat Exchanger Working under Supercritical Conditions in a Solar Organic Rankine Cycle Installation
Marija Lazova, Henk Huisseune, Alihan Kaya, Steven Lecompte, George Kosmadakis, Michel De Paepe
November 28, 2018 (v1)
Keywords: concentrated PV collectors, heat exchanger design, helical coil heat exchanger, organic Rankine cycle (ORC), supercritical heat transfer
Worldwide interest in low grade heat valorization using organic Rankine cycle (ORC) technologies has increased significantly. A new small-scale ORC with a net capacity of 3 kW was efficiently integrated with a concentrated solar power technology for electricity generation. The excess heat source from Photovoltaic (PV) collectors with a maximum temperature of 100 °C was utilized through a supercritical heat exchanger that uses R-404A as working medium. By ensuring supercritical heat transfer leads to a better thermal match in the heat exchanger and improved overall cycle efficiency. A helical coil heat exchanger was designed by using heat transfer correlations from the literature. These heat transfer correlations were derived for different conditions than ORCs and their estimated uncertainty is ~20%. In order to account for the heat transfer correlation uncertainties this component was oversized by 20%. Next, a prototype was built and installed in an integrated concentrated photovoltaic... [more]
Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part B: Application on a Case Study
Angelo La Seta, Andrea Meroni, Jesper Graa Andreasen, Leonardo Pierobon, Giacomo Persico, Fredrik Haglind
November 28, 2018 (v1)
Keywords: axial turbine, cycle optimization, mean line model, organic Rankine cycle (ORC), Surrogate Model, turbine design, turbine performance
Organic Rankine cycle (ORC) power systems have recently emerged as promising solutions for waste heat recovery in low- and medium-size power plants. Their performance and economic feasibility strongly depend on the expander. The design process and efficiency estimation are particularly challenging due to the peculiar physical properties of the working fluid and the gas-dynamic phenomena occurring in the machine. Unlike steam Rankine and Brayton engines, organic Rankine cycle expanders combine small enthalpy drops with large expansion ratios. These features yield turbine designs with few highly-loaded stages in supersonic flow regimes. Part A of this two-part paper has presented the implementation and validation of the simulation tool TURAX, which provides the optimal preliminary design of single-stage axial-flow turbines. The authors have also presented a sensitivity analysis on the decision variables affecting the turbine design. Part B of this two-part paper presents the first applic... [more]
Development and a Validation of a Charge Sensitive Organic Rankine Cycle (ORC) Simulation Tool
Davide Ziviani, Brandon J. Woodland, Emeline Georges, Eckhard A. Groll, James E. Braun, W. Travis Horton, Martijn van den Broek, Michel De Paepe
November 28, 2018 (v1)
Keywords: charge-based solver, cycle modeling, organic Rankine cycle, scroll expander, single-screw expander
Despite the increasing interest in organic Rankine cycle (ORC) systems and the large number of cycle models proposed in the literature, charge-based ORC models are still almost absent. In this paper, a detailed overall ORC simulation model is presented based on two solution strategies: condenser subcooling and total working fluid charge of the system. The latter allows the subcooling level to be predicted rather than specified as an input. The overall cycle model is composed of independent models for pump, expander, line sets, liquid receiver and heat exchangers. Empirical and semi-empirical models are adopted for the pump and expander, respectively. A generalized steady-state moving boundary method is used to model the heat exchangers. The line sets and liquid receiver are used to better estimate the total charge of the system and pressure drops. Finally, the individual components are connected to form a cycle model in an object-oriented fashion. The solution algorithm includes a prec... [more]
Performance Analysis of a Grid-Connected Upgraded Metallurgical Grade Silicon Photovoltaic System
Chao Huang, Michael Edesess, Alain Bensoussan, Kwok L. Tsui
November 27, 2018 (v1)
Keywords: data filtering, degradation rate, performance ratio, photovoltaic, upgraded metallurgical grade silicon
Because of their low cost, photovoltaic (PV) cells made from upgraded metallurgical grade silicon (UMG-Si) are a promising alternative to conventional solar grade silicon-based PV cells. This study investigates the outdoor performance of a 1.26 kW grid-connected UMG-Si PV system over five years, reporting the energy yields and performance ratio and estimating the long-term performance degradation rate. To make this investigation more meaningful, the performance of a mono-Si PV system installed at the same place and studied during the same period of time is presented for reference. Furthermore, this study systematizes and rationalizes the necessity of a data selection and filtering process to improve the accuracy of degradation rate estimation. The impact of plane-of-array irradiation threshold for data filtering on performance ratio and degradation rate is also studied. The UMG-Si PV system’s monthly performance ratio after data filtering ranged from 84% to 93% over the observation per... [more]
The Misselhorn Cycle: Batch-Evaporation Process for Efficient Low-Temperature Waste Heat Recovery
Moritz Gleinser, Christoph Wieland
November 27, 2018 (v1)
Keywords: batch evaporation, dynamic simulation, waste heat recovery
The concept of the Misselhorn cycle is introduced as a power cycle that aims for efficient waste heat recovery of temperature sources below 100 °C. The basic idea shows advantages over a standard Organic Rankine Cycle (ORC) in overall efficiency and utilization of the heat source. The main characteristic of this cycle is the use of at least three parallel batch evaporators instead of continuous heat exchangers. The operational phases of the evaporators are shifted so that there is always one vaporizer in discharge mode. A transient MATLAB® model (The MathWorks: Natick, MA, USA) is used to simulate the achievable performance of the Misselhorn cycle. The calculations of the thermodynamic states of the system are based on the heat flux, the equations for energy conservation and the equations of state found in the NIST Standard Reference Database 23 (Reference Fluid Thermodynamic and Transport Properties - REFPROP, National Institute of Standards and Technology: Gaithersburg, MD, USA). In... [more]
Modelling the Influence of Climate on the Performance of the Organic Rankine Cycle for Industrial Waste Heat Recovery
Ivan Korolija, Richard Greenough
November 27, 2018 (v1)
Keywords: climate, cooling tower, dry condenser, Energy Efficiency, organic Rankine cycle (ORC), recuperator, waste heat
This paper describes a study of the relative influences of different system design decisions upon the performance of an organic Rankine cycle (ORC) used to generate electricity from foundry waste heat. The design choices included concern the working fluid, whether to use a regenerator and the type of condenser. The novelty of the research lies in its inclusion of the influence of both the ORC location and the auxiliary electricity used by the pumps and fans in the ORC power system. Working fluids suitable for high temperature applications are compared, including three cyclic siloxanes, four linear siloxanes and three aromatic fluids. The ORC is modelled from first principles and simulation runs carried out using weather data for 106 European locations and a heat input profile that was derived from empirical data. The impact of design decisions upon ORC nominal efficiency is reported followed by the impact upon annual system efficiency in which variations in heat input and the condition... [more]
Integrated SNG Production in a Typical Nordic Sawmill
Sennai Mesfun, Jan-Olof Anderson, Kentaro Umeki, Andrea Toffolo
November 27, 2018 (v1)
Keywords: b-IGCC, bio-SNG, HEATSEP method, process integration, sawmill, techno-economic evaluation
Advanced biomass-based motor fuels and chemicals are becoming increasingly important to replace fossil energy sources within the coming decades. It is likely that the new biorefineries will evolve mainly from existing forest industry sites, as they already have the required biomass handling infrastructure in place. The main objective of this work is to assess the potential for increasing the profit margin from sawmill byproducts by integrating innovative downstream processes. The focus is on the techno-economic evaluation of an integrated site for biomass-based synthetic natural gas (bio-SNG) production. The option of using the syngas in a biomass-integrated gasification combined cycle (b-IGCC) for the production of electricity (instead of SNG) is also considered for comparison. The process flowsheets that are used to analyze the energy and material balances are modelled in MATLAB and Simulink. A mathematical process integration model of a typical Nordic sawmill is used to analyze the... [more]
Energy Transformations in a Self-Excited Switched Reluctance Generator
Abelardo Martinez-Iturbe, Francisco Jose Perez-Cebolla, Bonifacio Martín-del-Brío, Carlos Bernal, Antonio Bono-Nuez
November 27, 2018 (v1)
Keywords: AC generators, parametric oscillators, reluctance generators, tunable oscillators
Wind generation systems require mechanisms that allow optimal adaptation of the generator to varying wind speed and to extract maximum energy from the wind. Robust and affordable high-performance methods are also needed for isolated sites. This paper takes this approach, in which an AC switched reluctance generator is used as a generator with a variable rotor speed. Although the voltage obtained is of insufficient quality to connect the generator directly to the power grid, this kind of generator can be used in isolated sites to charge a battery bank with a simple bridge rectifier. Due to the nonlinear behavior of the machine with the position and current, along with the alternating nature of the current that circulates through its phases, the machine experiences cyclical energy transformations of a mechanical, electrical and magnetic nature. This paper analyzes these transformations for the purpose of providing guidelines for machine design and optimization as a wind turbine in isolat... [more]
Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids
Jesper G. Andreasen, Martin R. Kærn, Leonardo Pierobon, Ulrik Larsen, Fredrik Haglind
November 27, 2018 (v1)
Keywords: cost estimation, heat exchanger design, low temperature heat, multi-objective optimization, organic Rankine cycle, zeotropic mixture
For zeotropic mixtures, the temperature varies during phase change, which is opposed to the isothermal phase change of pure fluids. The use of such mixtures as working fluids in organic Rankine cycle power plants enables a minimization of the mean temperature difference of the heat exchangers, which is beneficial for cycle performance. On the other hand, larger heat transfer surface areas are typically required for evaporation and condensation when zeotropic mixtures are used as working fluids. In order to assess the feasibility of using zeotropic mixtures, it is, therefore, important to consider the additional costs of the heat exchangers. In this study, we aim at evaluating the economic feasibility of zeotropic mixtures compared to pure fluids. We carry out a multi-objective optimization of the net power output and the component costs for organic Rankine cycle power plants using low-temperature heat at 90 ∘ C to produce electrical power at around 500 kW. The primary outcomes... [more]
Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part A: Turbine Model
Andrea Meroni, Angelo La Seta, Jesper Graa Andreasen, Leonardo Pierobon, Giacomo Persico, Fredrik Haglind
November 27, 2018 (v1)
Keywords: axial turbine design, combined optimization, organic Rankine cycle (ORC), turbine experimental validation, turbine sensitivity analysis
Axial-flow turbines represent a well-established technology for a wide variety of power generation systems. Compactness, flexibility, reliability and high efficiency have been key factors for the extensive use of axial turbines in conventional power plants and, in the last decades, in organic Rankine cycle power systems. In this two-part paper, an overall cycle model and a model of an axial turbine were combined in order to provide a comprehensive preliminary design of the organic Rankine cycle unit, taking into account both cycle and turbine optimal designs. Part A presents the preliminary turbine design model, the details of the validation and a sensitivity analysis on the main parameters, in order to minimize the number of decision variables in the subsequent turbine design optimization. Part B analyzes the application of the combined turbine and cycle designs on a selected case study, which was performed in order to show the advantages of the adopted methodology. Part A presents a... [more]
Thermal Efficiency of Cogeneration Units with Multi-Stage Reheating for Russian Municipal Heating Systems
Evgeny Lisin, Alexander Sobolev, Wadim Strielkowski, Ivan Garanin
November 27, 2018 (v1)
Keywords: cogeneration, combined-cycle power plant, energy policy, heat supply, power utilities, Russian Federation, thermal efficiency, urban electric power
This paper explores the layout of an optimum process for supplying heat to Russian municipal heating systems operating in a market environment. We analyze and compare the standard cogeneration unit design with two-stage reheating of service water coming from controlled extraction locations and layouts that employ three in-line reheaters with heat the supply controlled by a rotary diaphragm and qualitative/quantitative methods (so-called “uncontrolled extraction”). Cogeneration unit designs are benchmarked in terms of their thermal efficiency expressed as a fuel consumption rate. The specific fuel consumption rate on electricity production is viewed as a key parameter of thermal efficiency.
Waste Heat Recovery of a PEMFC System by Using Organic Rankine Cycle
Tianqi He, Rongqi Shi, Jie Peng, Weilin Zhuge, Yangjun Zhang
November 27, 2018 (v1)
Keywords: heat pump, organic Rankine cycle, PEMFC, waste heat recovery
In this study, two systems are brought forward to recover the waste heat of a proton exchange membrane fuel cell (PEMFC), which are named the organic Rankine cycle (ORC), and heat pump (HP) combined organic Rankine cycle (HPORC). The performances of both systems are simulated on the platform of MATLAB with R123, R245fa, R134a, water, and ethanol being selected as the working fluid, respectively. The results show that, for PEMFC where operating temperature is constantly kept at 60 °C, there exists an optimum working temperature for each fluid in ORC and HPORC. In ORC, the maximal net power can be achieved with R245fa being selected as the working fluid. The corresponding thermal efficiency of the recovery system is 4.03%. In HPORC, the maximal net power can be achieved with water being selected in HP and R123 in ORC. The thermal efficiency of the recovery system increases to 4.73%. Moreover, the possibility of using ORC as the cooling system of PEMFC is also studied. The heat released f... [more]
Buck Converter with Soft-Switching Cells for PV Panel Applications
Cheng-Tao Tsai, Wang-Min Chen
November 27, 2018 (v1)
Keywords: electromagnetic interference (EMI), hard-switching, maximum-power-point-tracking (MPPT), metal-oxide-semiconductor-field-effect-transistor (MOSFET), soft-switching, zero-voltage-switching (ZVS)
In power conversion of photovoltaic (PV) energy, a hard-switching buck converter always generates some disadvantages. For example, serious electromagnetic interference (EMI), high switching losses, and stresses on an active switch (metal-oxide-semiconductor-field-effect-transistor, MOSFET), and high reverse-recovery losses of a freewheeling diode result in low conversion efficiency. To release these disadvantages, a buck converter with soft-switching cells for PV panel applications is proposed. To create zero-voltage-switching (ZVS) features of the active switches, a simple active soft-switching cell with an inductor, a capacitor, and a MOSFET is incorporated into the proposed buck converter. Therefore, the switching losses and stresses of the active switches and EMI can be reduced significantly. To reduce reverse-recovery losses of a freewheeling diode, a simple passive soft-switching cell with a capacitor and two diodes is implemented. To verify the performance and the feasibility of... [more]
Optimum Electric Boiler Capacity Configuration in a Regional Power Grid for a Wind Power Accommodation Scenario
Da Liu, Guowei Zhang, Baohua Huang, Weiwei Liu
November 27, 2018 (v1)
Keywords: combined heat and power, electric boiler, optimum capacity, wind power accommodation
Wind power generation reduces our reliance on fossil fuels and can thus reduce environmental pollution. However, rapid wind power development has caused various issues related to power grid restructuring. A high proportion of the generating capacity of northeast China is based on combined heat and power (CHP), whose inflexible response to the peak regulation of power grids hinders the ability to accommodate wind power; thus, wind power curtailment is prevalent. Electric boilers can directly consume the excess wind power to supply heat during low load periods and thus mitigate the heat supply stress of CHP units. Therefore, electric boilers improve the power grid’s ability to accommodate additional wind power. From a regional power grid perspective, this paper discussed the feasibility of such a strategy for increasing the ability to accommodate wind power during the heat supply season. This paper analysed the optimum electric boiler capacity configuration of a regional power grid based... [more]
Development and Simulation of a Type of Four-Shaft ECVT for a Hybrid Electric Vehicle
Yong Zhang, Xuerui Ma, Chengliang Yin, Shifei Yuan
November 27, 2018 (v1)
Keywords: configuration design, ECVT, multi-mode hybrid electric vehicle (HEV), optimal control, power-split
In hybrid electric vehicles with power-split configurations, the engine can be decoupled from the wheel and operated with improved fuel economy, while the entire efficiency of the powertrain is affected by the circular electric power flow. Two planetary gear (2-PG) sets with adding brakes/clutches, namely a type of four shaft elelctric continuously variable transmission (ECVT) can provide multi-mode operation for the powertrain and extend the efficient area. First, a conventional 2-PG AT (Automatic Transmission) architecture is investigated. By analyzing and comparing the connection and operating modes based on the kinematic relationship and lever analogy, a feasible four-shaft ECVT architecture with two brakes and two simplified versions are picked. To make a trade-off between fuel economy and configuration complexity, an instantaneous optimal control strategy based on the equivalent consumption minimization strategy (ECMS) concept is then developed and employed as the unified optimiz... [more]
A Comparative Study of Open and Closed Heat-Engines for Small-Scale CHP Applications
Ian W. Eames, Kieran Evans, Stephen Pickering
November 27, 2018 (v1)
Keywords: combined heat and power, heat engine cycles, recuperated Joule cycle, Stirling cycle, thermodynamic efficiency, thermodynamic performance
In this paper the authors compare and contrast open and closed-cycle heat engines. First of all, by way of example and to aid discussion, the performance of proprietary externally heated closed-cycle Stirling engines is compared with that of internally heated open Otto cycle engines. Both types of engine have disadvantages and merits and this suggested that in order to accommodate the best of both engine types an externally-heated open-cycle engine might offer a more satisfactory solution for small-scale combined heat and power (CHP) systems. To investigate this possibility further the paper goes on to compare the performance of externally-heated and recuperated Joule hot-air cycle engines with that of an externally-heated closed Stirling cycle engines. The results show that an externally heated recuperated open Joule cycle engine can exceed that of a closed cycle Stirling engine operating between the same heat source and sink temperatures when a variable temperature heat source is use... [more]
Revisting the Simultaneous Process Optimization with Heat Integration Problem: Updated model
Rahul Anantharaman
November 21, 2018 (v1)
Keywords: Heat integration, Pinch operator, Process integration
Simultaneous process optimization and heat integration is essential in the optimal design and operation of process plants with high energy efficiency. This document revisits the pinch location method and updates the compact formulation for simultaneous process optimization with heat integration presented by Anantharaman et al at FOCAPD 2014.
Field Study on Humidification Performance of a Desiccant Air-Conditioning System Combined with a Heat Pump
Koichi Kawamoto, Wanghee Cho, Hitoshi Kohno, Makoto Koganei, Ryozo Ooka, Shinsuke Kato
November 16, 2018 (v1)
Keywords: dedicated outdoor air system (DOAS), desiccant, heat pump, humidification
A desiccant air-conditioning system was developed as a latent-load-processing air conditioner in a dedicated outdoor air system during the summer. This study investigated the application of this air-conditioning system to humidification during the winter without using make-up water, thereby eliminating the cause of microbial contamination in air-conditioning systems. The experiments were conducted with a system used for summer applications to determine the feasibility of adsorbing vapor from outdoor air and supplying it to an indoor space. The humidification performance, energy efficiency, and operating conditions were examined. Although the conditions were subpar because the experiments were performed with an actual dedicated outdoor air system, the results showed that it is possible to supply air with a minimum humidity ratio of 5.8 g/kg dry air (DA) when the humidity ratio of outdoor air ranges from 1.8 to 2.3 g/kg DA. The minimum humidification performance required for a dedicated... [more]
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