Dynamic Performance of Conventional and Electrically Activated Engine Thermostats

2001 ◽  
Author(s):  
L. Alan Gunter ◽  
M. Razi Nalim
Keyword(s):  
Heat Transfer ◽  
Dynamic Performance ◽  
Control Device ◽  
The Road ◽  
Engine Control System ◽  
Passive Devices ◽  
Heating Device ◽  
Set Up ◽  
Spool Valve ◽  
Engine Coolant

Abstract This study concerns the dynamic performance of passive and active wax-actuator driven thermostats. The study is extended to wax actuator driven thermostats that have been fitted with a heating device, such that the thermostat can be actuated electrically. The thermostat valve type chosen for this study is a balanced, sleeve-type thermostat typically used in large over-the-road and industrial diesel engines. The valve operates like a spool valve to direct the flow of the engine coolant to the bypass, the heat exchanger, or partially to each. Since conventional thermostats are passive devices they lag in response to dynamic engine conditions, and under certain circumstances overheating can occur as a result of the device’s inability to respond quickly. Also, conventional thermostats are designed to protect an engine against overheating year round. Therefore, a thermostat designed to protect against overheating in the summer will often result in an overcooling condition in the winter. One possible solution to the problem is to control the thermostat electrically through the electronic engine control system, or other system, making the thermostat an active control device instead of a passive one. In this study, a mathematical model is developed to determine wax temperature, and thereby predict the thermostat operation and response. The wax temperature depends on the heat transfer from the engine coolant through the brass cup that encapsulates the wax, as well as heat transfer from the heater. The simulations are compared with measurements of temperature, thermostat position and flow at several locations around the thermostat in an experimental set-up. The outcome is used to analyze the accuracy of the methods used in the thermodynamic calculations.

A fuzzy evaluation method of road vehicle automatic weighing instrument in dynamic force metrological performance

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1365-1372
Author(s):  
Xiaohui Mao ◽  
Liping Fei ◽  
Xianping Shang ◽  
Jie Chen ◽  
Zhihao Zhao
Keyword(s):  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Evaluation Model ◽  
Dynamic Performance ◽  
Dynamic Force ◽  
Fuzzy Evaluation ◽  
Road Vehicle ◽  
Evaluation Standard ◽  
The Road ◽  
Metrological Performance

The measurement performance of road vehicle automatic weighing instrument installed on highways is directly related to the safety of roads and bridges. The fuzzy number indicates that the uncertain quantization problem has obvious advantages. By analyzing the factors affecting the metrological performance of the road vehicle automatic weighing instrument, combined with the fuzzy mathematics theory, the weight evaluation model of the dynamic performance evaluation of the road vehicle automatic weighing instrument is proposed. The factors of measurement performance are summarized and calculated, and the comprehensive evaluation standard of the metering performance of the weighing equipment is obtained, so as to realize the quantifiable analysis and evaluation of the metering performance of the dynamic road vehicle automatic weighing instrument in use, and provide data reference for adopting a more scientific measurement supervision method.

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

scholarly journals Sustainable Streetscape and Built Environment Designs around BRT Stations: A Stated Choice Experiment Using 3D Visualizations

2021 ◽  
Vol 13 (12) ◽  
pp. 6594
Author(s):  
Ahmad Adeel ◽  
Bruno Notteboom ◽  
Ansar Yasar ◽  
Kris Scheerlinck ◽  
Jeroen Stevens
Keyword(s):  
Built Environment ◽  
Mass Transit ◽  
Local Context ◽  
Transit Oriented Development ◽  
Commercial Building ◽  
Related Factors ◽  
Housing Projects ◽  
The Road ◽  
Development Goals ◽  
Set Up

The incompatibility between the microscale-built environment designs around mass transit stations and stakeholders’ preferences causes dissatisfaction and inconvenience. The lack of a pedestrian-friendly environment, uncontrolled development patterns, traffic and parking issues make the street life vulnerable and unattractive for users, and affect the mass transit usage. How to design the streetscapes around mass transit stations to provide a user-friendly street environment is a crucial question to achieve sustainable transit-oriented development goals. To recognize the specific attributes of streetscape environment relevant in local context of BRT Lahore, this paper presents the results of a visual preference experiment in which nine attributes of built environment were systematically varied across choice sets. Multinomial logit models were set up to identify the preferences of three target groups: BRT users, commercial building users and residents at different locations. The research indicates that not only the road-related factors (bike lane and sidewalk widths, crossings facilities, street greenery) have a significant influence on people’s preference but also that building heights, and the typology of buildings and housing projects around BRT corridor have shaped these preferences. When planning and designing urban design projects around mass transit projects, these significant attributes should be considered.

Wave propagation improvement in two-dimensional bond-based peridynamics model

2021 ◽  
pp. 095440622098555
Author(s):  
Reza Alebrahim ◽  
Pawel Packo ◽  
Mirco Zaccariotto ◽  
Ugo Galvanetto
Keyword(s):  
Wave Propagation ◽  
Dynamic Performance ◽  
Numerical Dispersion ◽  
Motion Modeling ◽  
Minimization Method ◽  
Irregular Wave ◽  
Point Collocation ◽  
Potential Applications ◽  
Non Local ◽  
Set Up

In this study, methods to mitigate anomalous wave propagation in 2-D Bond-Based Peridynamics (PD) are presented. Similarly to what happens in classical non-local models, an irregular wave transmission phenomenon occurs at high frequencies. This feature of the dynamic performance of PD, limits its potential applications. A minimization method based on the weighted residual point collocation is introduced to substantially extend the frequency range of wave motion modeling. The optimization problem, developed through inverse analysis, is set up by comparing exact and numerical dispersion curves and minimizing the error in the frequency-wavenumber domain. A significant improvement in the wave propagation simulation using Bond-Based PD is observed.

Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

2021 ◽  
pp. 875608792110260
Author(s):  
ME Ismail ◽  
MM Awad ◽  
AM Hamed ◽  
MY Abdelaal ◽  
EB Zeidan
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Film Cooling ◽  
Radiation Heat Transfer ◽  
Absolute Error ◽  
Numerical Results ◽  
Upper Lip ◽  
Original Design ◽  
Blown Film ◽  
Set Up

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

Measuring heavy traffic with WIM-ROAD and WIM-BRIDGE systems in an urban environment

2021 ◽  
Author(s):  
Maarten Soudijn ◽  
Sebastiaan van Rossum ◽  
Ane de Boer
Keyword(s):  
Heavy Traffic ◽  
Pressure Sensors ◽  
Strain Sensors ◽  
Traffic Load ◽  
Structural Safety ◽  
Special Focus ◽  
The Road ◽  
Weigh In Motion ◽  
Set Up ◽  
Calibration Program

<p>In this paper we present weight measurements of urban heavy traffic comparing two different Weigh In Motion (WIM) systems. One is a WIM-ROAD system using Lineas quartz pressure sensors in the road surface. The other is a WIM-BRIDGE system using optical fibre-based strain sensors which are applied under the bridge to the bottom fibre of a single span of the bridge deck. We have designed our tests to determine which system is most suited to Amsterdam. We put special focus on the accuracy that each system can achieve and have set up an extensive calibration program to determine this. Our ultimate goal is to draw up a realistic traffic load model for Amsterdam. This model would lead to a recommendation that can be used to re- examine the structural safety of existing historic bridges and quay walls, in addition to the current traffic load recommendations.</p>

scholarly journals HOT WIRE METHOD FOR THE THERMAL CHARACTERIZATION OF MATERIALS: INVERSE PROBLEM APPLICATION

2003 ◽  
Vol 2 (2) ◽  
Author(s):  
S. André ◽  
B. Rémy ◽  
F. R. Pereira ◽  
N. Cella ◽  
A. J. Silva Neto
Keyword(s):  
Heat Transfer ◽  
Thermal Characterization ◽  
Hot Wire ◽  
Confidence Bounds ◽  
Linear Temperature ◽  
Direct Model ◽  
Electrical Analogy ◽  
Wire Method ◽  
Characterization Of Materials ◽  
Set Up

An experimental set-up of the hot wire method is presented. The present design allows the measurement of the temperatures at two different points on the heating wire with an acquisition system that performs measurements at a frequency of 1kHz with a 12 bit numerical converter. An analytical solution for the direct model for the time dependent problem of heat transfer is employed. It is based on the quadrupole method which basically consists in a transfer matrix approach which is possible through the use of Laplace transforms. It extends the electrical analogy of heat transfer problems using the notion of impedance, and allows to take into account the thermal behavior of the wire, as well as contact resistance and heat loss effects in a very simple straightforward way. In the identification process carried on the temperature experimental data relies on a sampling of the data that is logarithmically spaced in time. The initial guesses for the thermal conductivity values are obtained applying the well known and ideal model of the linear temperature evolution versus the logarithm of the time. These values are used to start up the algorithms that are applied in the minimization of the cost functional of the squared residues between measured and calculated temperatures. The precision of the estimates is assessed with the calculated confidence bounds obtained by the variance-covariance matrix at the converged solution.

scholarly journals Heat and mass transfer in a metal hydride reactor: combining experiments and mathematical modelling

2021 ◽  
Vol 2057 (1) ◽  
pp. 012122
Author(s):  
D O Dunikov ◽  
V I Borzenko ◽  
D V Blinov ◽  
A N Kazakov ◽  
I A Romanov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Mass Flow ◽  
Metal Hydride ◽  
Porous Metal ◽  
Control Device ◽  
Variable Permeability ◽  
Flow Control Device ◽  
Porous Domain

Abstract Heat transfer in porous metal hydride (MH) beds determines efficiency of MH devices. We present a COMSOL Multiphysics numerical model and experimental investigation of heat and mass transfer in a MH reactor filled with 4.69 kg of AB5 type alloy (Mm0.8La0.2Ni4.1Fe0.8Al0.1). To achieve an agreement between the model and experiments it is necessary to include a flow control device (inlet valve or flow regulator) into the model. We propose a simplified and easy-to-calculate boundary condition based on a porous domain with variable permeability at reactor inlet. The permeability of the domain is connected with hydrogen mass flow by a PID controller. Thus, boundary conditions for the inlet pressure and mass flow are coupled and heat transfer inside the reactor could be calculated without additional assumptions applied to heat and mass transfer in the MH bed.

Design of a Thermostat for Precise Temperature Control From −190 Deg to +650 Deg C

1969 ◽  
Vol 91 (2) ◽  
pp. 168-172
Author(s):  
J. Ansari ◽  
W. Leidenfrost ◽  
R. Oldenburger
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Temperature Control ◽  
Hypothetical Case ◽  
Heat Transfer Medium ◽  
System Parameters ◽  
Set Up ◽  
Proportional Controller ◽  
Cylindrical Block ◽  
Selection Of

A proposed apparatus for controlling temperatures from −190 deg to +650 deg with an estimated accuracy of 0.001 deg C is described. The apparatus utilizes helium as the heat transfer medium. The selection of the gain constants of the controller depends upon the system parameters. The hypothetical case of a solid cylindrical block with an integral plus proportional controller is considered, the differential equations are set up, and a graphical scheme is presented for the selection of the controller constants.

Study of Electrostatic-Induced Jumping Droplets on Superhydrophobic Surfaces

2017 ◽  
Author(s):  
B. Traipattanakul ◽  
C. Y. Tso ◽  
Christopher Y. H. Chao
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Electrostatic Force ◽  
Droplet Radius ◽  
Inertia Force ◽  
Resistance Force ◽  
Average Charge ◽  
Electrical Voltage ◽  
Fluid Systems ◽  
Set Up

Condensation of water vapor is an important process utilized in energy/thermal/fluid systems. When droplets coalesce on the non-wetting surface, excess surface energy converts to kinetic energy leading to self-propelled jumping of merged droplets. This coalescing-jumping-droplet condensation can better enhance heat transfer compared to classical dropwise condensation and filmwise condensation. However, the resistance force can cause droplets to return to the surface. These returning droplets can either coalesce with neighboring droplets and jump again, or adhere to the surface. As time passes, these adhering droplets can become larger leading to progressive flooding on the surface, limiting heat transfer performance. However, an electric field is known to be one of the effective methods to prevent droplet return and to address the progressive flooding issue. Therefore, in this study, an experiment is set up to investigate the effects of applied electrical voltages between two parallel copper plates on the jumping height with respect to the droplet radius and to determine the average charge of coalescing-jumping-droplets. Moreover, the gravitational force, the drag force, the inertia force and the electrostatic force as a function of the droplet radius are also discussed. The gap width of 7.5 mm and the electrical voltages of 50 V, 100 V and 150 V are experimentally investigated. Droplet motions are captured with a high-speed camera and analyzed in sequential frames. The results of the study show that the applied electrical voltage between the two plates can reduce the resistance force due to the droplet’s inertia and can increase the effects of the electrostatic force. This results in greater jumping heights and the jumping phenomenon of some bigger-sized droplets. With the same droplet radius, the greater the applied electrical voltage, the higher the coalescing droplet can jump. This work can be utilized in several applications such as self-cleaning, thermal diodes, anti-icing and condensation heat transfer enhancement.

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