Showing papers on "Gas compressor published in 2015"
TL;DR: In this paper, detailed energy and exergy analysis of four different supercritical CO2 Brayton cycle configurations were performed with and without reheat, and the effect of turbine inlet temperature and the cycle configuration on the thermal performance was analyzed.
228 citations
TL;DR: Equipment- and site-level methane emissions from 45 compressor stations in the transmission and storage (T&S) sector of the US natural gas system were measured, including 25 sites required to report under the EPA greenhouse gas reporting program (GHGRP).
Abstract: Equipment- and site-level methane emissions from 45 compressor stations in the transmission and storage (TS the highest emitting 10% of sites (including two superemitters) contrib...
141 citations
TL;DR: In this article, a novel cryogenic air separation process with LNG (liquefied natural gas) cold energy utilization that produces liquid nitrogen and oxygen is proposed and analyzed.
140 citations
TL;DR: This paper deals with a high-order sliding mode (HOSM) approach to the observer-based output feedback control of a proton exchange membrane (PEM) fuel cell (FC) system consisting of a compressor, a supply manifold, an FC stack, and a return manifold.
Abstract: This paper deals with a high-order sliding mode (HOSM) approach to the observer-based output feedback control of a proton exchange membrane (PEM) fuel cell (FC) system consisting of a compressor, a supply manifold, an FC stack, and a return manifold. The treatment is based on a lumped parameter nonlinear modeling of the PEM FC system under study. The suggested scheme assumes the availability for measurements of readily accessible quantities such as the compressor angular velocity, the load current, and the supply and return manifold pressures. The control task is formulated in terms of regulating the oxygen excess ratio (which is estimated by a nonlinear finite-time converging HOSM observer) to a suitable set-point value by using, as adjustable input variable, the compressor supply voltage. The proposed observer embeds an original synergic combination between second- and third-order sliding mode (SM) algorithms. The controller also uses a second-order SM algorithm complemented by a novel tuning procedure, supported by local linearization and frequency-domain arguments, which allows the designer to enforce a practical SM regime with some prespecified and user-defined characteristics. Thoroughly discussed simulations results certify the satisfactory performance of the proposed approach.
109 citations
TL;DR: In this paper, a modified model is used to increase the precision of the gasifier thermodynamic model, and the authors deal with thermodynamic and economic analysis of a combined gas turbine and organic rankine cycle integrated with a biomass gasifier.
106 citations
TL;DR: In this article, the potential of improving the energy efficiency of a conventional cryogenic air separation unit (ASU) was investigated through modelling and simulation using Aspen Plus v 8.1.
103 citations
TL;DR: In this article, the performance of a supercritical gas Brayton cycle with CO2-based binary mixtures as the working fluids has been studied, and an in-house code has been developed to determine the cycle efficiency and the amounts of heat transfer in the HTR (high temperature recuperator) and the LTR (low temperature rerouting) with different CO2/additive gas ratios.
90 citations
TL;DR: In this article, a Korean research team designed the SCIEL (Supercritical CO2 Integral Experiment Loop) to achieve higher efficiency with higher pressure ratio with S-CO2 power cycle compared to other pre-existing facilities.
87 citations
TL;DR: In this paper, an experimental investigation on heat transfer with porous media inserts during compression and expansion was conducted for a pressure ratio of 10 and 6, respectively, and the results showed that the surface area increase was the predominant cause for the improvement in performance.
85 citations
TL;DR: In this paper, the first combustion system designed for the use of biomass derived product gases in micro gas turbines was presented, and the operating performance of the combustion system and of the micro gas turbine Turbec T100 was analyzed experimentally with synthetically mixed fuel compositions.
84 citations
TL;DR: A new geometric programming approach for optimizing compressor operation in natural gas pipelines is presented and it is shown that the geometric programming algorithm consistently outperforms approaches that mimic the existing state of practice.
Abstract: Natural gas transmission pipelines are complex systems whose flow characteristics are governed by challenging nonlinear physical behavior. These pipelines extend over hundreds and even thousands of miles. Gas is typically injected into the system at a constant rate, and a series of compressors is distributed along the pipeline to boost the gas pressure to maintain system pressure and throughput. These compressors consume a portion of the gas, and one goal of the operator is to control the compressor operation to minimize this consumption while satisfying pressure constraints at the gas load points. The optimization of these operations is computationally challenging. Many pipelines simply rely on the intuition and prior experience of operators to make these decisions. Here, we present a new geometric programming approach for optimizing compressor operation in natural gas pipelines. Using models of real natural gas pipelines, we show that the geometric programming algorithm consistently outperforms approaches that mimic the existing state of practice.
Patent•
08 Jun 2015
TL;DR: In this paper, the authors present a system for treating liquefied gas, which includes an evaporation gas supply line connected from a LNG storage tank to a LPG consumer.
Abstract: According to an embodiment of the present invention, a system for treating liquefied gas includes: an evaporation gas supply line connected from a liquefied gas storage tank to a liquefied gas consumer; an evaporation gas compressor provided on the evaporation gas supply line, and configured to compress evaporation gas generated from the liquefied gas storage tank; an evaporation gas heat exchanger provided in the upstream of the evaporation gas compressor on the evaporation gas supply line, and configured to perform heat exchange between evaporation gas compressed by the evaporation gas compressor and collected along an evaporation gas collect line branching off from the upstream of the liquefied gas consumer, and evaporation gas supplied from the liquefied gas storage tank; a Joule-Thomson valve provided in the downstream of the evaporation gas heat exchanger based on a flow of evaporation gas collected along the evaporation gas collect line, and configured to primarily decompress evaporation gas compressed by the evaporation gas compressor; an evaporation gas expander configured to secondarily decompress evaporation gas primarily decompressed by the Joule-Thomson valve; and a gas-liquid separator configured to separate flash gas from evaporation gas decompressed by the Joule-Thomson valve. According to the present invention, the system for treating liquefied gas performs a first decompression of evaporation gas using the Joule-Thomson valve, and a second decompression thereof using the evaporation gas expander when liquefying the evaporation gas to sequentially perform an isenthalpic process and an isentropic process, thereby improving the efficiency of evaporation gas liquefaction, compared to perform the entire decompression process using the Joule-Thomson valve. In addition, rotational power generated by the evaporation gas expander driven by the introduction of evaporation gas may be used as power to the evaporation gas expander to reduce power, thereby the efficiency of the LNG treatment system.
TL;DR: In this paper, the experimental testing of an ORC integrate in a 2-liter turbocharged gasoline engine using ethanol as working fluid was conducted, where the main components of the cycle are a boiler, a condenser, a pump and a swash-plate expander.
TL;DR: In this article, an interdisciplinary simulation model of the electrochemical machining (ECM) process for aero engine blades is set up and compared to optical measurements of actual manufactured workpieces.
TL;DR: An experimental study of the performance of a hybrid humidification-dehumidification water desalination and air conditioning system using vapor compression refrigeration cycle is presented and investigated in this article.
TL;DR: In this article, the main exergy parameters of an aircraft gas turbine engine are introduced while the exergy destruction rates within the engine components are split into endogenous/exogenous and avoidable/unavoidable parts.
TL;DR: A new ejector enhanced auto-cascade refrigeration cycle using R134a/R23 refrigerant mixture is proposed in this paper, where an ejector is used to recover part of the work that would otherwise be lost in the throttling processes.
TL;DR: In this paper, a thermodynamic model for a hybrid solar gas-turbine power plant is presented, taking into account the most important losses sources: those coming from heat losses in the solar subsystem, those in the combustion chamber, those associated to the Brayton cycle, and those heat loss in the heat exchangers connecting subsystems.
TL;DR: In this paper, the authors compared the performance of commercially available 170kW vapor compression chiller with equivalent three configurations (parallel, series and combined series-parallel) of VCAIRS (vapor compression-absorption integrated refrigeration system) based on combined energy, exergy, economic and environmental (4E) analyses.
TL;DR: In this article, an organic rankine cycle (ORC) with a scroll expander with varying displacement is studied. And the experimentally obtained isentropic efficiency, thermodynamic and heat transfer models of ORC are established on the basis of submodels of the main apparatuses.
TL;DR: In this paper, a combined defrosting cycle with DHBD and the accumulator heating method is developed to overcome lower discharge temperature of compressor, and the overall heating capacity of the combined DHBD-IH cycle including the IH cycle was 2.5 times higher than that of the RCD cycle.
TL;DR: In this paper, the authors present an overview of CO2 heat pump water heater for residential use in Japan, including the general background, current market, and the technology evolvement of the transcritical CO2 system, especially on the key components like compressor and gas cooler.
Abstract: The present study presents an overview of CO2 heat pump water heater for residential use in Japan. The contents include the general background, current market, and the technology evolvement of the transcritical CO2 system, especially on the key components like compressor and gas cooler. Some cutting edge technology associated with the high efficient compressors and its integration with expander, such as swing compressor, sub-compressor, two-stage compressor, scroll expander, and dual-sided scroll-type expander are elaborated in this review. Some ingenious tube designs to promote the performance of gas cooler are also studied. In practice, the dominant thermal resistance may occur in the CO2 side or water side, thereby implementing twisted tube or dimple tubes may be quite effective. The placement of enhancement on the water side is especially effective when the operational pressure is close to the critical pressure whereas heat transfer enhancement is more helpful if the operational pressure is comparatively high. For augmentation on the CO2 side, it would be more beneficial to place enhancement a distance away from the pseudo-critical region.
TL;DR: In this article, the authors proposed a nonlinear multi-objective optimization scheme to tune the shape of the component map curves in order to meet the targeted set of engine measurements.
Abstract: Gas turbines are faced with new challenges of increasing flexibility in their operation while reducing their life cycle costs, leading to new research priorities and challenges. One of these challenges involves the establishment of high fidelity, accurate, and computationally efficient engine performance simulation, diagnosis, and prognosis schemes, which will be able to handle and address the gas turbine's ever-growing flexible and dynamic operational characteristics. Predicting accurately the performance of gas turbines depends on detailed understanding of the engine components behavior that is captured by component performance maps. The limited availability of these maps due to their proprietary nature has been commonly managed by adapting default generic maps in order to match the targeted off-design or engine degraded measurements. Although these approaches might be suitable in small range of operating conditions, further investigation is required to assess the capabilities of such methods for use in gas turbine diagnosis under dynamic transient conditions. The diversification of energy portfolio and introduction of distributed generation in electrical energy production have created need for such studies. The reason is not only the fluctuation in energy demand but also more importantly the fact that renewable energy sources, which work with conventional fossil fuel based sources, supply the grid with varying power that depend, for example, on solar irradiation. In this paper, modeling methods for the compressor and turbine maps are presented for improving the accuracy and fidelity of the engine performance prediction and diagnosis. The proposed component map fitting methods simultaneously determine the best set of equations for matching the compressor and the turbine map data. The coefficients that determine the shape of the component map curves have been analyzed and tuned through a nonlinear multi-objective optimization scheme in order to meet the targeted set of engine measurements. The proposed component map modeling methods are developed in the object oriented MATLAB/SIMULINK environment and integrated with a dynamic gas turbine engine model. The accuracy of the methods is evaluated for predicting multiple component degradations of an engine at transient operating conditions. The proposed adaptive diagnostics method has the capability to generalize current gas turbine performance prediction approaches and to improve performance-based diagnostic techniques. Copyright © 2015 by ASME.
TL;DR: In this article, a modified dual-evaporator CO2 transcritical refrigeration cycle with two-stage ejector was proposed, and the effect of some key parameters on the thermodynamic performance of the modified cycle were theoretically investigated based on energetic and exergetic analyses.
Patent•
19 May 2015TL;DR: In this paper, a trim air line branching off from the process air line upstream of the air conditioning unit and being configured such that trim air flows through the trim line, the trim air having been separated from the compressed process air flowing through the line.
Abstract: An aircraft air conditioning system comprises a process air line configured to supply compressed process air provided by a process air source to an air conditioning unit of the aircraft air conditioning system and a trim air line branching off from the process air line upstream of the air conditioning unit and being configured such that trim air flows through the trim air line, the trim air having been branched off from the compressed process air flowing through the process air line. A compressor is arranged in the trim air line and is configured to compress the trim air flowing through the trim air line. A turbine of the aircraft air conditioning system is configured to drive the compressor. A cabin exhaust air line is configured to supply cabin exhaust air discharged from an aircraft cabin to the turbine for driving the turbine.
TL;DR: In this article, an ejector associated with an additional flash tank is introduced to enhance the overall system performance at low ambient temperature, and then compared with those of the basic vapor injection cycle (BVIC), the performance characteristics of the EVIC may show its promise in heat pump applications.
Patent•
13 May 2015
TL;DR: In this paper, a method for controlling an air-conditioner is presented, which includes the steps that A, the operating mode of the air conditioner is detected in real time; B, when the air conditioning system is in a refrigeration mode or in a dehumidification mode, the indoor environment temperature and the first indoor environment humidification of the AC is collected, and the operating time of the AAF in the refrigeration or dehumidity mode is counted.
Abstract: The invention discloses a method for controlling an air-conditioner. The method includes the steps that A, the operating mode of the air-conditioner is detected in real time; B, when the air-conditioner is in a refrigeration mode or in a dehumidification mode, the indoor environment temperature and the first indoor environment humidification of the air-conditioner are collected, and the operating time of the air-conditioner in the refrigeration mode or in the dehumidification mode is counted; C, when the operating time of the air-conditioner in the refrigeration mode or in the dehumidification mode reaches first preset time, whether the judging conditions that the first indoor environment humidification is larger than first preset humidification and the indoor environment temperature belongs to a first preset temperature interval can be met at the same time or not is judged, if yes, the step D is executed, and if not, the step A is executed; D, the operating maximum frequency of a compressor of the air-conditioner is set to be a first frequency, and the current operating frequency of the compressor of the air-conditioner is lowered according to the first frequency. The invention further discloses a system for controlling the air-conditioner. By means of the method and system for controlling the air-conditioner, the maximum operating frequency of the compressor of the air-conditioner is lowered, and condensation is prevented.
Patent•
13 May 2015
TL;DR: In this article, an air conditioning system consisting of an indoor unit and an outdoor unit communicated with the indoor unit through a refrigerant pipeline, and an expansion valve was arranged between the inside unit and the outside unit.
Abstract: The invention provides an air conditioning system The air conditioning system comprises an indoor unit (1) and an outdoor unit (2) communicated with the indoor unit (1) through a refrigerant pipeline (3) An expansion valve is arranged between the indoor unit (1) and the refrigerant pipeline (3) The opening degree of the expansion valve is controlled by a first sensor detecting a first measurement value of the refrigerant pipeline (3) The outdoor unit (2) is provided with a compressor and a draught fan The compressor is controlled by a second sensor detecting a second measurement value of the refrigerant pipeline (3), so that the frequency is adjusted The rotating speed of the draught fan is adjusted according to the air outlet temperature of the compressor The air conditioning system can achieve automatic optimal matching between the indoor unit and the outdoor unit according to the load change without communication
TL;DR: In this paper, the authors presented the thermoeconomic optimization of LiBr/H2O-R134a compression-absorption cascade refrigeration cycle, which revealed the optimum generator temperature, condenser temperature, absorber temperature and condenser compression section.
TL;DR: In this article, a mapping of the thermodynamic performance of different supercritical CO2 cycle configurations that encompass a 250-850 °C TIT (turbine inlet temperature) range is presented.