Experimental Study on Two-Stage Cascade Low Temperature Pre-Cooling Equipment

2010 ◽  
Vol 42 ◽  
pp. 322-325
Author(s):  
Xiu Fang Liu ◽  
Fa Hui Wang ◽  
Fan Mao Meng
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Low Temperature ◽  
Cooling Capacity ◽  
Temperature Cycle ◽  
Test Bed ◽  
Two Stage ◽  
Overload Protection ◽  
Set Up ◽  
Two Stages

A two-stage cascade pre-cooling test bed was designed and set up to develop a -30°C /-60°C pre-cooling equipment. An internal heater exchanger and a condenser were set in low-temperature cycle. Theoretically the two stages can work stably at setting temperature and the low-temperature cycle can operate independently with aided starting of the high-temperature cycle. The experimental results indicate that the test bed can provide cooling capacity steadily at -46°C and -100°C respectively and the low-temperature cycle cannot operate alone for compressor overload protection. Based on the analysis, the possible reasons and detailed suggestions were put forward.

Systematic Fluid Selection for Organic Rankine Cycles (ORC) and Performance Analysis for a Combined High and Low Temperature Cycle

2015 ◽  
Author(s):  
Maximilian Rödder ◽  
Matthias Neef ◽  
Christoph Laux ◽  
Klaus-P. Priebe
Keyword(s):  
High Temperature ◽  
Performance Analysis ◽  
Low Temperature ◽  
Waste Heat ◽  
Selection Process ◽  
Working Fluid ◽  
Temperature Cycle ◽  
Two Stage ◽  
Working Fluids ◽  
Wide Range

The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree of freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination and tolerance criteria. For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time the selection process is applied to a two-stage reference cycle which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature and a low temperature cycle in which the condensation heat of the high temperature (HT) cycle provides the heat input of the low temperature (LT) cycle. After the fluid selection process the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17,4% in the high temperature cycle with Toluene as the working fluid and 6,2% in low temperature cycle with iso-Butane as the working fluid. The electric efficiency of the cogeneration plant increases from 40,4% to 46,97% with the both stages of the two-stage ORC in operation.

scholarly journals Effects of Double-Ageing Heat Treatments on the Microstructure and Mechanical Behaviour of a Ti-3.5Al-5Mo-4V Alloy

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 209
Author(s):  
Xuanming Ji ◽  
Panpan Ge ◽  
Song Xiang ◽  
Yuanbiao Tan
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Low Temperature ◽  
Mechanical Behaviour ◽  
Ageing Time ◽  
Two Stage ◽  
Ageing Treatment ◽  
Ω Phase ◽  
Α Phase ◽  
Temperature Ageing

In this work, the effect of double-ageing heat treatments on the microstructural evolution and mechanical behaviour of a metastable β-titanium Ti-3.5Al-5Mo-4V alloy is investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-ageing treatments are composed of low-temperature pre-ageing and high-temperature ageing, where the low-temperature pre-ageing is conducted at 300 °C or 350 °C for different times, and the high-temperature ageing is conducted at 500 °C for 8 h. The results show that the phase transformation sequence is altered with the time spent during the first ageing stage, the isothermal ω phase is precipitated in the pre-ageing process of the alloy at 300 °C and 350 °C with the change in the ageing time, and the ω phase is finally transformed into the α phase with the extension of pre-ageing time. The existence time of the ω phase is shortened as the pre-ageing temperature increases. The microhardness of the alloy increases with increasing pre-ageing time and temperature. Compared with single-stage ageing, the ω phase formed in the pre-ageing stage changes the response to subsequent high-temperature ageing. After the two-stage ageing treatment, the precipitation size of the α phase is obviously refined after the double-ageing treatment. A microhardness test shows that the microhardness of the two-stage aged alloy increases with extended pre-ageing time.

Systematic Fluid Selection for Organic Rankine Cycles and Performance Analysis for a Combined High and Low Temperature Cycle

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Maximilian Roedder ◽  
Matthias Neef ◽  
Christoph Laux ◽  
Klaus-P. Priebe
Keyword(s):  
Performance Analysis ◽  
Low Temperature ◽  
Power Plants ◽  
Waste Heat ◽  
Selection Process ◽  
Working Fluid ◽  
Temperature Cycle ◽  
Two Stage ◽  
Working Fluids ◽  
Wide Range

The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree-of-freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic, and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination (EC) and tolerance criteria (TC). For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time, the selection process is applied to a two-stage reference cycle, which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature (HT) and a low temperature (LT) cycle in which the condensation heat of the HT cycle provides the heat input of the LT cycle. After the fluid selection process, the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17.4% in the HT cycle with toluene as the working fluid and 6.2% in LT cycle with isobutane as the working fluid. The electric efficiency of the cogeneration plant increases from 40.4% to 46.97% with the both stages of the two-stage ORC in operation.

Preparation of a silver nanoparticle-based dual-functional sensor using a complexation–reduction method

2015 ◽  
Vol 17 (33) ◽  
pp. 21243-21253 ◽  
Author(s):  
Fwu-Long Mi ◽  
Shao-Jung Wu ◽  
Wen-Qi Zhong ◽  
Cheng-Yu Huang
Keyword(s):  
Silver Nanoparticles ◽  
High Temperature ◽  
Low Temperature ◽  
Silver Nanoparticle ◽  
Reduction Method ◽  
Ag Nps ◽  
Two Stage ◽  
Temperature Reduction ◽  
Dual Functional

A dual-functional sensor based on silver nanoparticles was synthesized by a two-stage procedure consisting of a low-temperature chitosan–Ag+ complexation followed by a high-temperature reduction of the complex to form chitosan-capped silver nanoparticles (CS-capped Ag NPs).

Experimental Study of a Novel Indirect Evaporative Cooler

2013 ◽  
Vol 671-674 ◽  
pp. 2547-2550
Author(s):  
Yu Gang Wang ◽  
Jia Ping Liu ◽  
Huang Xiang
Keyword(s):  
Experimental Study ◽  
Dew Point ◽  
Test Bed ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Air Volume ◽  
Cooling Section ◽  
Evaporative Cooler ◽  
Secondary Air ◽  
Set Up

Set up a test-bed, test the pre-cooling section, cooling section, and the units consist of them separately, then analysis the data. Within the experimental range, the best ratio of the secondary air volume and the primary air volume is 1.2 for the pre-cooling section, for the cooling section is 1.69. The outlet air temperature is below its wet bulb temperature for the units, and higher than its dew point temperature.

Study on the Mechanical Property of Nomex Fiber in Different Temperature

2014 ◽  
Vol 887-888 ◽  
pp. 895-898
Author(s):  
Gen Yang Cao ◽  
Xing Fang Xiao ◽  
Wei Lin Xu
Keyword(s):  
Mechanical Property ◽  
High Temperature ◽  
Low Temperature ◽  
Temperature Cycle ◽  
High Tech ◽  
New Materials ◽  
Breaking Elongation ◽  
Temperature Conditions ◽  
World Today ◽  
The World

Nomex (Aramid 1313) is the best high temperature resistant high-tech new materials in the world today. In this paper, Nomex was treated in the experiment of high temperature, low temperature, high and low temperature conditions. The results show that the high temperature affects the strength and breaking elongation for nomex fiber. Low temperature and high & low temperature cycle does not affect much on the strength and breaking elongation.

Stress Intensity Factor of Thermal Fatigue Crack in High Temperature

2012 ◽  
Vol 581-582 ◽  
pp. 677-680
Author(s):  
Ming Yan ◽  
Hao Chuan Li ◽  
Lin Li
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
High Temperature ◽  
Stress Intensity ◽  
Low Temperature ◽  
Intensity Factor ◽  
Thermal Fatigue ◽  
Kinematic Hardening ◽  
Temperature Cycle ◽  
Thermal Fatigue Crack

Stress intensity factor of thermal fatigue crack was calculated within one cycle by using finite element method in consideration of the multi-linear kinematic hardening characteristic of a material. The affection of loading sequence to stress intensity factor was studied under circularly variational temperature by comparing to that in one cycle. The low temperature cycle can not affect the stress intensity factor of latter cycles with high temperature; but high temperature cycle can affect the stress intensity factor of latter cycles with low temperature, and make it be equal to that of the high temperature cycle.

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