Analysis Of Cooldown Research Articles

Study on Cool-down Analysis Technology for Large Scale Liquid Hydrogen Receiving Terminal

Study on Cool-down Analysis Technology for Large Scale Liquid Hydrogen Receiving Terminal

The 1-D analysis of cool down simulation of vehicle HVAC system

In this paper, a detailed combined 1-D model of HVAC systems of a vehicle were developed by using the LMS imagine LAB AMESIM software package. The numerical simulations were considered for soaking and cool down analysis under different environmental conditions. The thermal performance of different refrigerants as R-134a and R-1234yf were evaluated in terms of thermal performance and energy consumption. According to the soaking simulation results, the cabin air temperature values ranged from 49?C to 57?C in general. The maximum increase in cabin air temperature value was about 22?C obtained for 1000 W/m2 solar load. The total time until reaching the steady-state conditions for a target temperature value (23.5?C) was different for all simulations. The total time was calculated as 910 seconds for 1000 W/m2 solar load by using R-134a refrigerant loop. The results also showed that although the thermal performance of R-134a was slightly better, R-1234yf can be used due to its environmental properties with acceptable performance. The calculated COP values during cooldown analysis were ranged from 1.71 to 4.52 in general. The minimum value was obtained for the cases which had a maximum solar load and higher cabin interior temperature values. The calculated temperature data for soaking and cool down analysis were in good agreement with the reference data presented in this study. These numerical results are very important for reducing the thermal load of the vehicle cabin considering energy consumption of the HVAC system for different thermal conditions.

Numerical analysis of cooldown of large magnets for low energy beam line for Facility for Antiproton and Ion Research

Numerical analysis of cooldown of large magnets for low energy beam line for Facility for Antiproton and Ion Research

Practical study of optimizing the cool-down scenario for the KSTAR helium refrigeration system

The cooling of superconducting (SC) magnet system for fusion device is the first procedure of the experiment. The Korea Superconducting Tokamak Advanced Research (KSTAR) device is fully SC tokamak that is made of NbTi and Nb3Sn. The KSTAR SC magnets are composed of 16 Toroidal Field (TF) coils and 14 Poloidal Field (PF) coils with 300 tons of cold mass. A Helium Refrigeration System (HRS) with 9kW@4.5K was installed and has been operated since 2008 to cool the SC magnets and keep all magnets at appropriate temperature conditions. This paper describes and analyzes the operational result of HRS during the KSTAR cool-down in 2008 and 2013. According to the cool-down analysis, the larger cryogenic helium flow from HRS made more efficient cooling of SC magnets. Furthermore, the study of cool-down optimization based on practical approach is presented and the build-up of control logic by using of cool-down optimization is also discussed.

A numerical cool-down analysis for Dewar-detector assemblies cooled with Joule–Thomson cryocoolers

Joule–Thomson (J–T) cryocoolers are commonly in use for rapid cool-down of Infra-Red (IR) detectors. The cool-down time is governed both by the J–T cryocooler performances and the Dewar structure, which is usually geometrically complicated. A finite-element model of the complete Dewar-Detector-Cooler Assembly (DDCA) is developed. The analysis calculates the heat transfer in the Dewar and the J–T cryocooler, the coolant flow rate, the pressure drop in the vessel that supplies the coolant to the J–T cryocooler, and the pressure drop in the low pressure stream of the heat exchanger that determines the pressure in the evaporator. A verification of the analysis is conducted against experimental results with a single cryocooler at a single scenario and the model is further validated against eleven other experimental results. A satisfactory agreement is obtained between the analysis and the experimental results.

Thermo-hydraulic analysis of the cool-down of the EDIPO test facility

The first cool-down of the EDIPO (European DIPOle) test facility is foreseen to take place in 2011 by means of the existing 1.2 kW cryoplant at EPFL-CRPP Villigen. In this work, the thermo-hydraulic analysis of the EDIPO cool-down is performed in order both to assess the its duration and to optimize the procedure. The cool-down is driven by the helium flowing in both the outer cooling channel and in the windings connected hydraulically in parallel. We take into account limitations due to the pressure drop in the cooling circuit and the refrigerator capacity as well as heat conduction in the iron yoke. Two schemes of the hydraulic cooling circuit in the EDIPO windings are studied (coils connected in series and coils connected in parallel). The analysis is performed by means of an analytical model complemented by and numerical model. The results indicate that the cool-down to 5 K can be achieved in about 12 days.

Numerical analysis of cooldown and warmup for the Large Hadron Collider

As the basis of studies, the paper presents the inventory of components and materials for LHC magnets, especially for main dipoles and quadrupoles firstly. Then a mathematical model and analytical method for LHC transient modes, such as cooldown and warmup of a magnet, a standard cell and the eight LHC sectors, has been developed on the basis of the up-to-date layout of the LHC machine, and validated by experimental data. The model and method do not only consider the momentum and continuity equations as well as the energy equations for helium and materials, but also take into account the pressure evolution in the different headers of the cryogenic distribution line and the effect of the pressure drop across the cryogenic valves. Based on the simulation results, the heat transfer in the magnets has been studied and the transient modes optimized.

Three Mile Island Unit 2 Degraded Core Heatup and Cooldown Analysis

A two-dimensional finite element model was developed to simulate the Three Mile Island Unit 2 core heatup between 174 and 224 min and the subsequent cooling of the consolidated core region after th...