Comparison of thermal-hydraulic network control strategies

2003 ◽  
Vol 217 (1) ◽  
pp. 35-47
Author(s):  
W Franco ◽  
M Sen ◽  
K T Yang ◽  
R L McClain
Keyword(s):  
Thermal Load ◽  
Control Strategies ◽  
Temperature Drop ◽  
Network Control ◽  
Air Cooling ◽  
Primary Loop ◽  
Special Cases ◽  
Control Schemes ◽  
Hydraulic Network ◽  
Cooling Coil

A dynamic thermal-hydraulic analysis of strategies used for the control of hydronic piping and heat exchanger networks is carried out. Three common temperature control methods are analysed and compared using a mathematical model. For this purpose a general thermal network with a primary loop, a secondary loop and a bypass that has the three control systems as special cases is proposed. The primary loop includes a chiller, while the secondary has a water-air cooling coil which serves as a thermal load. Integral controllers are used to vary the valve settings to control the air temperature leaving the cooling coil. The system responses for each of the three control schemes as a function of the thermal load are then compared to assess their relative merits using the temperature drop in the chiller as a criterion.

DYNAMICS OF THERMAL-HYDRAULIC NETWORK CONTROL STRATEGIES

2004 ◽  
Vol 17 (3) ◽  
pp. 161-179 ◽  
Author(s):  
Walfre Franco ◽  
Mihir Sen ◽  
K. T. Yang ◽  
Rodney McClain
Keyword(s):  
Control Strategies ◽  
Network Control ◽  
Hydraulic Network

Experimental Comparison of Thermal Control Strategies in Piping Networks

2003 ◽  
Author(s):  
Walfre Franco ◽  
Mihir Sen ◽  
K. T. Yang ◽  
Rodney L. McClain
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Load ◽  
Control Strategies ◽  
Cooling Water ◽  
Thermal Control ◽  
Control Technique ◽  
Experimental Comparison ◽  
Primary Loop ◽  
Heating And Cooling

This manuscript presents an experimental study of three thermal control strategies commonly used in heating and cooling of buildings. The strategies are defined by the variables to be controlled, the hardware used for control and the piping arrangement. The experimental facility includes three heat exchangers within secondary loops that are connected to a primary loop. A different control technique is applied to each secondary loop. A heat exchanger on the primary loop delivers cooling water to the secondaries and receives warm water in return. Chilled water is provided by the building services. The thermal load to the heat exchangers is supplied by two water heaters which are located on a closed heating circuit. PID controllers are used to respond to changes in the thermal load. The temperature difference at the primary loop heat exchanger is used as a criterion for comparison to assess the relative merits and drawbacks of each strategy.

Comparison of thermal–hydraulic network control strategies

2003 ◽  
Vol 217 (1) ◽  
pp. 35-47 ◽  
Author(s):  
W Franco ◽  
M Sen ◽  
K T Yang ◽  
R L McClain
Keyword(s):  
Control Strategies ◽  
Network Control ◽  
Hydraulic Network

A Survey on Brachiation Robots: An Energy-Based Review

Robotica ◽  
2021 ◽  
pp. 1-13
Author(s):  
Sibyla Andreuchetti ◽  
Vinícius M. Oliveira ◽  
Toshio Fukuda
Keyword(s):  
Special Class ◽  
Control Strategies ◽  
Underactuated Systems ◽  
Decision Variable ◽  
Robot Dynamics ◽  
Technical Literature ◽  
Control Schemes

SUMMARY Many different control schemes have been proposed in the technical literature to control the special class of underactuated systems, the- so-called brachiation robots. However, most of these schemes are limited with regard to the method by which the robot executes the brachiation movement. Moreover, many of these control strategies do not take into account the energy of the system as a decision variable. To observe the behavior of the system’s, energy is very important for a better understanding of the robot dynamics while performing the motion. This paper discusses a variety of energy-based strategies to better understand how the system’s energy may influence the type of motion (under-swing or overhand) the robot should perform.

Main engine of transport ship inlet air cooling by ejector chiller

2020 ◽  
Vol 5 (3) ◽  
pp. 33-48
Author(s):  
Roman M. Radchenko1 ◽  
◽  
Dariusz Mikielewicz2 ◽  
Mykola I. Radchenko1 ◽  
Victoria S. Kornienko1 ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Air Temperature ◽  
Temperature Drop ◽  
Climatic Conditions ◽  
Air Cooling ◽  
Slow Speed ◽  
Exhaust Gases ◽  
Transport Ship ◽  
Main Engine

The efficiency of cooling the air at the inlet of marine slow speed diesel engine turbocharger by ejector chiller utilizing the heat of exhaust gases and scavenge air were analyzed. The values of air temperature drop at the inlet of engine turbocharger and corresponding decrease in fuel consumption of the engine at varying climatic conditions on the route line Odesa-Yokogama- Odesa were evaluated.

scholarly journals Effect of Cooling Flow on the Operation of a Hot Rotor-Gas Foil Bearing System

2012 ◽  
Author(s):  
Keun Ryu ◽  
Luis San Andrés
Keyword(s):  
Thermal Management ◽  
Flow Rate ◽  
System Integration ◽  
Damping Ratio ◽  
Temperature Drop ◽  
Test System ◽  
The Body ◽  
Air Cooling ◽  
Cooling Flow ◽  
Management Procedures

Gas foil bearings (GFBs) operating at high temperature rely on thermal management procedures that supply needed cooling flow streams to keep the bearing and rotor from overheating. Poor thermal management not only makes systems inefficient and costly to operate but could also cause bearing seizure and premature system destruction. This paper presents comprehensive measurements of bearing temperatures and shaft dynamics conducted on a hollow rotor supported on two first generation GFBs. The hollow rotor (1.36 kg, 36.51 mm OD and 17.9 mm ID) is heated from inside to reach an outer surface temperature of 120°C. Experiments are conducted with rotor speeds to 30 krpm and with forced streams of air cooling the bearings and rotor. Air pressurization in an enclosure at the rotor mid span forces cooling air through the test GFBs. The cooling effect of the forced external flows is most distinct when the rotor is hottest and operating at the highest speed. The temperature drop per unit cooling flow rate significantly decreases as the cooling flow rate increases. Further measurements at thermal steady state conditions and at constant rotor speeds show that the cooling flows do not affect the amplitude and frequency contents of the rotor motions. Other tests while the rotor decelerates from 30 krpm to rest show that the test system (rigid-mode) critical speeds and modal damping ratio remain nearly invariant for operation with increasing rotor temperatures and with increasing cooling flow rates. Computational model predictions reproduce the test data with accuracy. The work adds to the body of knowledge on GFB performance and operation and provides empirically derived guidance for successful rotor-GFB system integration.

An Overview of Different Indirect and Semi-Indirect Evaporative Cooling System for Study Potency of Nanopore Skinless Bamboo as An Evaporative Cooling New Porous Material

2021 ◽  
Vol 79 (2) ◽  
pp. 123-130
Author(s):  
I Nyoman Suprapta Winaya ◽  
Hendra Wijaksana ◽  
Made Sucipta ◽  
Ainul Ghurri
Keyword(s):  
Energy Consumption ◽  
Porous Material ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Temperature Drop ◽  
High Energy ◽  
Dew Point ◽  
Air Cooling ◽  
Evaporative Cooling System ◽  
Indirect Evaporative Cooling

The high energy consumption of compressor based cooling system has prompted the researchers to study and develop non-compressor based cooling system that less energy consumption, less environment damaging but still has high enough cooling performances. Indirect and semi indirect evaporative cooling system is the feasible non-compressor based cooling systems that can reach the cooling performance required. This two evaporative cooling system has some different in construction, porous material used, airflow scheme and secondary air cooling method used for various applications. This paper would report the cooling performances achieved by those two cooling system in terms of cooling efficiency, cooling capacity, wet bulb effectiveness, dew point effectiveness, and temperature drop. Porous material used in indirect and semi-indirect evaporative cooling would be highlighted in terms of their type, size, thickness and any other feature. The introduction of nanopore skinless bamboo potency as a new porous material for either indirect or semi-indirect evaporative cooling would be described. In the future study of nanopore skinless bamboo, a surface morphology and several hygrothermal test including sorption, water vapor transmission, thermal conductivity test would be applied, before it utilize as a new porous material for direct or semi indirect evaporative cooling.

Practical Fixed-Time Event-Triggered Time-Varying Formation Tracking Control for Disturbed Multi-Agent Systems with Continuous Communication Free

2020 ◽  
Vol 09 (01) ◽  
pp. 23-34
Author(s):  
Xiaofeng Chai ◽  
Jian Liu ◽  
Yao Yu ◽  
Jianxiang Xi ◽  
Changyin Sun
Keyword(s):  
Control Strategies ◽  
Fixed Time ◽  
Settling Time ◽  
Time Varying ◽  
Multi Agent Systems ◽  
Agent Systems ◽  
Formation Tracking ◽  
Control Schemes ◽  
Multi Agent ◽  
Event Triggered

In this paper, we study the practical fixed-time event-triggered time-varying formation tracking problem of leader-follower multi-agent systems with multi-dimensional dynamics. Fixed-time event-triggered control schemes with continuous communication and intermittent communication are developed, respectively. Continuous communication and measurement are avoided, and computation cost is reduced greatly in the latter scheme. And the settling time is to be specified regardless of initial states of agents. Meanwhile, tracking errors are adjustable as desired with expected settling time. It is demonstrated that time-varying formation tracking can be achieved under the two proposed control schemes and Zeno behavior can be excluded. Finally, numerical examples are provided to illustrate the effectiveness of the proposed control strategies.

First Test Results of a Haptic Tele-Operation System to Enhance Stability of Telescopic Handlers

2010 ◽  
Author(s):  
Stefano Cenci ◽  
Giulio Rosati ◽  
Damiano Zanotto ◽  
Fabio Oscari ◽  
Aldo Rossi
Keyword(s):  
Degrees Of Freedom ◽  
Force Feedback ◽  
Control Strategies ◽  
Input Device ◽  
Test Results ◽  
Operation System ◽  
Work Related ◽  
Control Schemes ◽  
Working Capability ◽  
Stiff Joint

According to a recent report of ILO (International Labour Organization), more than two million people die or loose the working capability every year because of accidents or work-related diseases. A large portion of these accidents are related to the execution of motion and transportation tasks involving heavy duty machines. The insufficient degree of interaction between the human operator and the machine may be regarded as one of the major causes of this phenomenon. The main goal of the tele-operation system presented in this paper is to both preserving slave (machine) stability, by reducing the inputs of slave actuators when certain unsafe working conditions occur, and improving the level of interaction at master (operator) side. Different control schemes are proposed in the paper, including several combinations of master and slave control strategies. The effectiveness of the algorithms is analyzed by presenting some experimental results, based on the use of a two degrees-of-freedom force feedback input device (with one active actuator and one passive stiff joint) coupled with a simulator of a telescopic handler.

Multiscale Control to Meet the Conflicting Nanoscale Performance Requirements

2005 ◽  
Author(s):  
Huzefa Shakir ◽  
Won-Jong Kim
Keyword(s):  
Degrees Of Freedom ◽  
Reference Model ◽  
Control Strategies ◽  
Mass Model ◽  
Integral Term ◽  
Six Degrees Of Freedom ◽  
Performance Requirements ◽  
Model Following ◽  
Control Schemes ◽  
Domain Performance

In this paper, we consider the problem of designing a multiscale control for plants with conflicting time-domain performance requirements. These results follow from the conventional optimal proportional-integral (PI) control. Four different design methods are proposed: (1) a controller-switch technique which makes use of employing two different controllers designed to meet two different performances and are switched during the course of operation, (2) an integral-reset scheme, which resets the integral term in the control law when the new reference point is reached, (3) controller-switch and integral-reset schemes put together to take benefits of both of them, (4) a model-following approach that uses a dynamic reference model without increasing the overall dimension of the system. The objective of the last scheme is to make the output of the plant track the output of the model as closely as possible. Stability analyses and a comparison between the performances of these methods are given. All these methods give better performances as compared with conventional control schemes. Block diagrams are given and step responses are obtained to demonstrate the proposed methods. A six degrees-of-freedom (DOFs) magnetically levitated (maglev) stage with a second-order pure-mass model has been used to demonstrate the capabilities of the aforementioned control strategies. These strategies are not plant-specific and may be generalized to any higher-order plant.

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