共查询到20条相似文献，搜索用时 250 毫秒
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本文笔者根据近15年来冷却塔在首都机场集中制冷系统中的实际应用,介绍了由于先前对于冷却塔运行、维护工作重视程度不够导致冷却塔效率下降,制约了整个制冷系统的正常运行,能源利用率大幅降低,后通过对冷却塔进行更新,集中制冷系统整体效率提升的实例。针对冷却塔改造前后不同效率的逆流式和横流式冷却塔在实际使用中对集中制冷系统和设备的影响进行分析,通过实际生产效果对比和经济性分析说明冷却塔在集中制冷系统中的重要作用。 相似文献
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蒸发循环制冷系统的研究是目前直升机上环控系统的一个研究重点.通过对直升机上传统制冷系统冷凝散热风道结构进行分析,发现其存在明显不足,然后在传统方案基础上提出新的优化方案,并进行计算分析对比了两种风道方案对散热的影响,最后通过某型机验证发现新的优化方案能使系统耗电量可减少2kVA以上,重量可减轻超过5kg,使用温度环境可... 相似文献
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本文介绍了起飞总质量法的估算模型,并以此计算了四种不同的制冷系统方案。通过必要的对比分析,说明该估算模型的合理性,可作为一种有效的飞机制冷系统评价方法。 相似文献
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Nassim Tahouni M. Hassan Panjeshahi Abtin Ataei 《Journal of The Franklin Institute》2011,348(7):1456-2446
A great deal of attention has been paid to design and optimization of low-temperature liquefaction and gas separation problems over the past years, due to their difficult nature. In this paper, two approaches featuring sequential and simultaneous methods for selection and arrangement of sub-ambient separation systems and their associated refrigeration cycles are compared. The effect of ignoring heat integration within the separation system and between the separation and refrigeration systems is addressed as well as fixing the sequence order of separation. The optimization is carried out using two famous stochastic search methods i.e. Genetic Algorithm (GA) and Simulated Annealing (SA). Three case studies are examined to illustrate the significant differences between optimization results. Also, the design optimality is re-checked with respect to usage of different refrigerants and the resulting structure is verified by application of a comprehensive exergy analysis. 相似文献
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文章主要介绍JZS-2F6.5A型压缩冷凝机组的结构与组成,包括：制冷压缩机主体,机组冷凝器与蒸发器,制冷剂的节流机构,机组的辅助装置,机组的压力表与压力控制器。压缩冷凝机组的检修要点,包括：检修的时间和内容,拆卸机组应注意的事项,主要零件的检查与修理。 相似文献
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改造小型冷库的控制电路,把原来的普通控制电路改造为PLC控制电路,改造后的控制系统有自动和手动功能,增设安全保护和互锁功能,还能自动报警,使冷库的功能稳定性和安全性得以全面提升,最后对改造后的冷库进行了性能调试。 相似文献
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The problem of position tracking for a tank gun control system with inertia uncertainty and external disturbance is investigated in this paper. The tank gun control system, demanding high tracking precision and stabilization precision, is a nonlinear system. Classical control methods are commonly used in the actual system, which is difficult to ensure high precision and high disturbance rejection capability. An active disturbance rejection control (ADRC) scheme is applied to guarantee the state variables of the closed loop system to converge to the reference state with the help of the extended state observer by estimating the inertia uncertainty and external disturbance. The basic theory of the ADRC is introduced here. According to the mathematical model, the parameters of ADRC are designed. Also, simulation results show that ADRC controller has advantages of high precision and high disturbance rejection ability. A comparison between ADRC and PID is also presented to show the effectiveness of the ADRC control strategy. 相似文献
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Heat effects in fixed-bed sorption columns are often quite large and have a pronounced effect on the sorption kinetics. Proper design of such systems must include consideration of these effects.A method is developed for computing the maximum possible bed temperature. The model is tested on two systems: (1) the Linde molecular sieve 4 A/water system and (2) the Alcoa activated alumina F-1/water system. Since the predicted temperatures appeared to be low for the latter system, the model was refined by the inclusion of the isosteric integral heat of adsorption. Tests on the activated alumina show considerable improvement.The isosteres of two sorption therm correlations are investigated. The results show that the heat of adsorption of water on the alumina varies logarithmically with sorbate concentration—approaching high values at low concentrations and approaching the heat of vaporization of water at high concentrations. The results also suggest that the isosteric heat of adsorption behavior may be of use in assessing the “goodness of fit” of sorption therm correlations. 相似文献
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本文分析了煤矿深井高温的原因,总结了非制冷降温、人工制冷水降温、制冰降温、压气节流降温技术、空气压缩制冷降温技术、分离式热管降温和采取个体防护等不同矿井降温技术的适宜条件及存在的问题.针对高温矿井热害这一客观存在的现象,在实际应用中因地制宜,利用不同降温方式,均可取得较好的经济效益和社会效益. 相似文献
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研究了受热阻、热漏和回热损失影响的不可逆斯特林制冷机制冷率和制冷系数的最高和最低界限。为斯特林制冷机工作参数的选择提供了两条有限时间热力学新准则。 相似文献
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《Journal of The Franklin Institute》2023,360(7):4675-4694
This paper addresses the control problem of an uncertain system suffering from an exogenous disturbance. A new degree of control freedom is developed to handle the problem based on the equivalent-input-disturbance (EID) approach. The effect of the disturbance and uncertainties is equivalent to that of a fictitious disturbance on the control input channel, which is called an EID. A state observer and an improved EID (IEID) estimator are devised to produce an estimate that is used to compensate for the disturbance and uncertainties in a control law. A second-order low-pass filter is employed in the estimator to provide a way to solve a tradeoff between disturbance rejection and noise suppression. The slope of the Bode magnitude curve at high frequencies is two times larger for the IEID estimator than for a conventional one. This makes the IEID estimator less sensitive to measurement noise and more practical. Sufficient analyses reveal the mechanism of disturbance rejection, uncertainty attenuation, and noise suppression of an IEID-based control system. A theorem is derived to guarantee system stability and a procedure is presented for system design. Simulations and experiments of the position control of a magnetic levitation system are carried out to show the validity of the presented method. 相似文献