Transient Simulation of Absorption Machines

1982 ◽  
Vol 104 (3) ◽  
pp. 197-203 ◽  
Author(s):  
D. K. Anand ◽  
R. W. Allen ◽  
B. Kumar
Keyword(s):  
Steady State ◽  
Lithium Bromide ◽  
Working Fluid ◽  
Cooling Load ◽  
Space Cooling ◽  
Start Up ◽  
Residual Capacity ◽  
Insight Into ◽  
Significant Factors ◽  
Steady State Performance

This paper presents a model for a water-cooled Lithium-Bromide/water absorption chiller and predicts its transient response both during the start-up phase and during the shutoff period. The simulation model incorporates such influencing factors as the thermodynamic properties of the working fluid, the absorbent, the heat-transfer configuration of different components of the chiller and related physical data. The time constants of different components are controlled by a set of key parameters that have been identified in this study. The results show a variable but at times significant amount of time delay before the chiller capacity gets close to its steady-state value. The model is intended to provide an insight into the mechanism of build-up to steady-state performance. By recognizing the significant factors contributing to transient degradation, steps can be taken to reduce such degradation. The evaluation of the residual capacity in the shut-off period will yield more realistic estimates of chiller COP for a chiller satisfying dynamic space cooling load.

Start-up and Steady-State Performance of a New Renewable Alcohol-To-Jet (ATJ) Fuel in Multiple Diesel Engines

2015 ◽  
Author(s):  
Terrence Dickerson ◽  
Andrew McDaniel ◽  
Sherry Williams ◽  
Dianne Luning-Prak ◽  
Len Hamilton ◽  
...  
Keyword(s):  
Steady State ◽  
Diesel Engines ◽  
Start Up ◽  
Steady State Performance

Start Up and Transient Response to Power Input of a Capillary Assisted Thermosyphon for Shipboard Electronics Cooling

2010 ◽  
Author(s):  
V. Tudor ◽  
M. Cerza
Keyword(s):  
Steady State ◽  
Flat Plate ◽  
Transient Response ◽  
Flow Rate ◽  
Heat Input ◽  
Electric Propulsion ◽  
Electronics Cooling ◽  
Working Fluid ◽  
Cold Plate ◽  
Start Up

The future capabilities of naval ships will be directly related to the electronic components used in advanced radar systems, fire control systems, electric propulsion and even electric weapons. The next generation of naval warships will fall under the concept of an all electric ship, where turbines convert all the power produced by the engine into electricity. This electrical power can then be distributed given the ship’s mission and operating profile. The current need for advanced electronics cooling techniques is paramount since power dissipation levels are rapidly exceeding the capabilities of forced air convection cooling. This paper reports an experimental investigation of the start-up and transient response to heat load change of a capillary assisted thermosyphon (CAT) for the shipboard cooling of electronics components. The capillary assisted thermosyphon differs from a capillary pumped loop or loop heat pipe system in that the basic cooling-loop is based on a thermosyphon. The capillary assist comes from the fact that there is a wicking structure in the flat evaporator plate. The wicking structure allows uniformly spread of the working fluid across the flat plate evaporator in the areas under the heat sources as well as providing additional capillary pumping assist to the loop. A vertical flat plate, CAT evaporator was designed and tested under a fixed thermal sink temperature of 21°C. The condenser cold plate cooling water flow rate was fixed as 3.785 liters per minute (i.e. 1 gpm). The heat input varied from 250 to 1000W — evenly spread over the area of the evaporator. The CAT flat plate evaporator performed very well under this range of heat inputs, sink temperature, and cold plate flow rate. The main result obtained showed that the CAT loop reached steady state operation within 10 min. to 15 min. The average plate temperature did not exceed 70°C for the maximum heat input of 1000W. The CAT evaporator operating temperature increased with increasing heat input for all conditions tested and reached 60°C at 1000W. The continuous and stable operation of the CAT loop during start-up, steady-state and during transient/sudden heat input variations indicates that the CAT loop is a viable solution for high flux electronics components cooling.

Quasi-steady-state performance of a heat pipe subjected to transient acceleration loadings

10.2514/3.895 ◽  
1997 ◽  
Vol 11 ◽  
pp. 306-309 ◽  
Author(s):  
Edwin H. Olmstead ◽  
Edward S. Taylor ◽  
Meng Wang ◽  
Parviz Moin ◽  
Scott K. Thomas ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Quasi Steady State ◽  
Steady State Performance

A Novel Control Scheme for PWM Boost Converter based on Sliding Mode Control using Particle Swarm Optimization

2020 ◽  
Vol 14 ◽  
Author(s):  
Gang Liu ◽  
Dong Qiu ◽  
Xiuru Wang ◽  
Ke Zhang ◽  
Huafeng Huang ◽  
...  
Keyword(s):  
Particle Swarm Optimization ◽  
Steady State ◽  
Sliding Mode ◽  
Particle Swarm ◽  
Mathematic Model ◽  
Absolute Error ◽  
Boost Converter ◽  
Sliding Mode Controller ◽  
Swarm Optimization ◽  
Steady State Performance

Background: The PWM Boost converter is a strongly nonlinear discrete system, especially when the input voltage or load varies widely, therefore, tuning the control parameters of which is a challenge work. Objective: In order to overcome the issues, particle swarm optimization (PSO) is employed for tuning the parameters of a sliding mode controller of a boost converter. Methods: Based on the analysis of the Boost converter model and its non-linear characteristics, a mathematic model of a boost converter with a sliding mode controller is built firstly. Then, the parameters of the Boost controller are adjusted based on the integrated time and absolute error (ITAE), integral square error (ISE) and integrated absolute error (IAE) indexes by PSO. Results: Simulation verification was performed, and the results show that the controllers tuned by the three indexes all have excellent robust stability. Conclusion: The controllers tuned by ITAE and ISE indexes have excellent steady-state performance, but the overshoot is large during the startup. The controller tuned by IAE index has better startup performance and slightly worse steady-state performance.

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