Error in Temperature Measurements Due to Conduction Along the Sensor Leads

1976 ◽  
Vol 98 (3) ◽  
pp. 491-495 ◽  
Author(s):  
B. S. Singh ◽  
A. Dybbs
Keyword(s):  
Temperature Distribution ◽  
The Body ◽  
True Temperature ◽  
Measured Temperature ◽  
Internal Temperature ◽  
Sensing Element ◽  
First Approximation ◽  
Immersion Thermocouple ◽  
Thermocouple Wire ◽  
Good Agreement

When a sensor is embedded in a solid body to measure its internal temperature, any conduction to, or from, its sensing element may cause the indicated temperature to be different from the true temperature. This paper describes an analysis of the error caused by conduction when there is an arbitrary temperature distribution in thebbody along the sensor. The sensor is modeled as a cylindrical fin and the appropriate conduction equation is solved. The solution gives a correction for the error which depends on such parameters as, depth of immersion, thermocouple wire and insulation properties, contact between the sensor and the body, and temperature distribution in the body. The latter may not be known, but the measured temperature distribution can be used as a first approximation. The corrected value can then be used to obtain a better estimate of the error. The results show good agreement with experimental observations.

scholarly journals Modelling thermal properties of large LED modules

2019 ◽  
Vol 37 (4) ◽  
pp. 628-638 ◽  
Author(s):  
Przemysław Ptak ◽  
Krzysztof Górecki ◽  
Barbara Dziurdzia
Keyword(s):  
Thermal Properties ◽  
Temperature Distribution ◽  
Power Dissipation ◽  
Thermal Model ◽  
Parameters Estimation ◽  
Internal Temperature ◽  
Practical Usefulness ◽  
Good Agreement

AbstractIn this paper a problem of modelling thermal properties of large LED modules is considered. The compact thermal model of such modules is proposed. The form of this model is presented and a method of parameters estimation is described. The practical usefulness of this model is verified experimentally by comparing the results of calculations and measurements of internal temperature of selected LEDs included in LED modules. The modules were fabricated by Fideltronic, Poland and measurements of temperature distribution on the surface of the modules at selected variants of power dissipation were performed at the Gdynia Maritime University. Good agreement between the results of measurements and modelling was obtained.

scholarly journals Analysis of the Temperature Distribution in a Refrigerated Truck Body Depending on the Box Loading Patterns

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2560
Author(s):  
Junhwi So ◽  
Sungyong Joe ◽  
Seonho Hwang ◽  
Soojin Jun ◽  
Seunghyun Lee
Keyword(s):  
Temperature Distribution ◽  
Temperature Sensor ◽  
Turbulence Models ◽  
The Body ◽  
Cold Chain ◽  
Cfd Modeling ◽  
Comsol Multiphysics ◽  
Measured Temperature ◽  
Loading Patterns ◽  
Higher Temperature

The main purpose of cold chain is to keep the temperature of products constant during transportation. The internal temperature of refrigerated truck body is mainly measured with a temperature sensor installed at the hottest point on the body. Hence, the measured temperature cannot represent the overall temperature values of transported products in the body. Moreover, the airflow pattern in the refrigerated body can vary depending on the arrangement of loaded logistics, resulting temperature differences between the transported products. In this study, the airflow and temperature change in the refrigerated body depending on the loading patterns of box were analyzed using experimental and numerical analysis methods. Ten different box loading patterns were applied to the body of 0.5 ton refrigerated truck. The temperatures inside boxes were measured depending on the loading patterns. CFD modeling with two different turbulence models (k-ε and SST k-ω) was developed using COMSOL Multiphysics for predicting the temperatures inside boxes loaded with different patterns, and the predicted data were compared to the experimental data. The k-ε turbulence model showed a higher temperature error than the SST k-ω model; however, the highest temperature point inside the boxes was almost accurately predicted. The developed model derived an approximate temperature distribution in the boxes loaded in the refrigerated body.

Measurement of Internal Temperature Distribution in PEMFCs by Nondestructive Inverse Method

2005 ◽  
Author(s):  
Mei-Hsia Chang ◽  
Chin-Hsiang Cheng
Keyword(s):  
Temperature Distribution ◽  
Outer Surface ◽  
Inverse Method ◽  
Initial Guess ◽  
Temperature Data ◽  
Membrane Electrode ◽  
Measured Temperature ◽  
Internal Temperature ◽  
Temperature Prediction ◽  
End Plate

A nondestructive inverse method is developed to determine the internal temperature distribution of PEMFCs. In this study, attention is focused on global measurement for the irregular temperature distribution at the interface between the carbon plate and the membrane electrode assembly (MEA) based on the measured temperature data on the outer surface of the end plate. In this report, a concept of point-by-point temperature prediction is adopted. This approach is particularly suitable for determining an irregular temperature distribution that is difficult to handle by the existing polynomial-function approach [1]. A number of test cases are considered in this study. Three irregular temperature functions are specified and regarded as exact temperature distributions for testing the performance of the approach. Influence of the uncertainties of the measured temperature data on the outer surface and the number of the temperature prediction points (NX×NY) on the end plate surface is evaluated. In addition, the effects of the initial guess on the uniqueness of the predictions are also investigated.

Enhanced Pixel by Pixel Emissivity Correction for Thermal Microscopy

2004 ◽  
Author(s):  
S.H. Goh ◽  
K.H. Yim ◽  
J.C.H. Phang ◽  
L.J. Balk
Keyword(s):  
Temperature Distribution ◽  
Transfer Function ◽  
Device Under Test ◽  
Temperature Error ◽  
True Temperature ◽  
Measured Temperature ◽  
Surface Emissivity ◽  
New Approach ◽  
Thermal Microscopy ◽  
Actual Temperature

Abstract In thermal microscopy, temperature error arises whenever a constant emissivity value is assumed for different materials. In this paper, we propose a new approach to eliminate these undesirable effects resulting from the ambiguous surface emissivity of materials. This method enables the compensated (true) temperature distribution of a device under test to be obtained from the measured temperature image. A transfer function that relates the measured and true temperature is formed to estimate the actual temperature distribution of a biased device to an accuracy of approximately 0.3-0.7K.

Semi Analytical Prediction of Automobile Body Temperature Distribution in the Top Coat Paint Oven

2009 ◽  
Author(s):  
P. Hanafizadeh ◽  
B. Sajadi ◽  
M. H. Saidi ◽  
H. Khalkhali ◽  
M. Taherraftar
Keyword(s):  
Temperature Distribution ◽  
Body Temperature ◽  
Thermal Behavior ◽  
The Body ◽  
Transient Temperature ◽  
Analytical Prediction ◽  
Experimental Procedure ◽  
Car Body ◽  
And Performance ◽  
Good Agreement

Automotive industry frequently needs to test new products, according to different production parameters, in order to determine the actual thermal behavior of bodies before mass production is implemented. Numerical simulation of these processes can reduce the very expensive and time consuming experimental procedures. For the drying and hardening process of the top paint applied in the coating process, the body temperature must be raised according to the paint manufacturer regulations. Consequently, prediction of temperature distribution of the car body during various zones of ovens is very vital in the design and performance analysis of the paint dryers. In this research, a novel semi-analytical approach has been used to predict the body temperature variation during the curing process. Considering the energy balance for the body, a set of differential equation has been extracted, depending on the oven zone. These equations can be solved numerically to find the transient temperature profile of the car body. Some parameters in these equations have been achieved by experimental procedure. The results show that the present model predictions are in a good agreement with the experimental data. Therefore, the developed model has a reasonable accuracy and can be used as an efficient robust approach to distinguish overall thermal behavior of the body. These techniques can be used to optimize the design of curing paint oven.

Impact of Cargo Stacking Modes on Temperature Distribution Inside Marine Reefer Containers

2017 ◽  
Vol 25 (03) ◽  
pp. 1750020 ◽  
Author(s):  
Ankang Kan ◽  
Jin Hu ◽  
Zhipeng Guo ◽  
Chuang Meng ◽  
Chen Chao
Keyword(s):  
Temperature Distribution ◽  
Heat Release ◽  
Internal Temperature ◽  
Temperature Distributions ◽  
Key Factor ◽  
Simulation Results ◽  
Cfd Method ◽  
Sidewall Surface ◽  
Good Agreement

The refrigerated/chilled quality of marine cargo is vitally influenced by the temperature distribution inside reefer container. The stacking mode is a key factor affecting temperature distribution. CFD method is employed to model and simulate a 20-ft standard reefer container, in which seven cargo stacking modes are emulated to numerically analyze the internal temperature distribution inside the container. The stacking cargo is assumed as solid stack without heat release and the variables, such as stack number, height, length and gap, are considered in seven simulation cases. The results show that the temperature distributions become disordered along with increase in the stack height; the temperature difference increase along with increase in the stack length; the temperature tends to be isothermal when the gap of the stacks or the space between the stack and sidewall surface is enlarging. The simulation results are in very good agreement with the experimental results.

Effect of Rake Face Design on Cutting Tool Temperature Distributions

1980 ◽  
Vol 102 (2) ◽  
pp. 123-128 ◽  
Author(s):  
P. K. Wright ◽  
S. P. McCormick ◽  
T. R. Miller
Keyword(s):  
Temperature Distribution ◽  
Cutting Tool ◽  
Contact Length ◽  
Measured Temperature ◽  
Rake Face ◽  
Low Carbon ◽  
Temperature Distributions ◽  
Metallographic Method ◽  
Carbon Iron ◽  
Good Agreement

Turning experiments have been carried out on a low carbon iron using steel tools of different side rake face geometry. Temperature distributions have been determined using a recently developed metallographic method. It has been found that when using tools which have a controlled chip-tool contact length of 0.5 mm. the temperatures are ∼30 per cent lower than when using conventional, 6 deg rake tools and, as a result, tool life is longer. Theoretical equations are described which allow the calculation of the temperature distribution along the chip tool interface and the tribological conditions in this region are also considered in detail. There is good agreement between the calculated and measured temperature distributions.

Experimental Analysis and Numerical Modeling of Microwave Reheating of Cylindrically Shaped Instant Rice

2014 ◽  
Vol 10 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Daming Fan ◽  
Chunxiang Li ◽  
Yi Li ◽  
Wei Chen ◽  
Jianxin Zhao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Internal Temperature ◽  
Microwave Application ◽  
Cooked Rice ◽  
Temperature Distributions ◽  
Rice Samples ◽  
Good Agreement

Abstract The purpose of this study was to develop a numerical model to predict the temperature distribution in cylindrically shaped cooked rice samples during microwave reheating and to give impetus to a uniform microwave-heating design. Cylindrically shaped instant rice was reheated by continuous microwave application, and the sample temperature was measured to determine the internal temperature profile which resulted in a desired uniformity of temperature observed using the non-uniformity temperature evaluation. A finite difference method was used to predict the temperature distribution of the cylindrical rice during microwave reheating and applying Lambert’s law to calculate the microwave power absorption in a large sample of cylindrically shaped instant rice. In order to solve the numerical model of heat transfer, the thermal and dielectric properties of instant rice were measured with respect to temperature. Our results showed that the temperature had a significant effect on the specific heat and dielectric loss of rice, while the thermal conductivity and dielectric constant were unaffected. The numerically predicted temperature distributions were in good agreement with the measured ones of instant rice.

Characteristics of Heat Transfer During Machining With Rotary Tools

2004 ◽  
Vol 126 (2) ◽  
pp. 404-407 ◽  
Author(s):  
H. A. Kishawy and ◽  
A. G. Gerber
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Rotational Speed ◽  
Measured Temperature ◽  
Tool Rotational Speed ◽  
Radial Temperature ◽  
Conservation Of Energy ◽  
Finite Volume Discretization ◽  
Heat Partitioning ◽  
Good Agreement

In this paper a model is developed to analyze heat transfer and temperature distribution resulting during machining with rotary tools. The presented model is based on a finite-volume discretization approach applied to a general conservation of energy statement for the rotary tool and chip during machining. The tool rotational speed is modeled and its effect on the heat partitioning between the tool and the chip is investigated. The model is also used to examine the influence of tool speed on the radial temperature distribution on the tool rake face. A comparison between the predicted and previously measured temperature data shows good agreement. In general the results show that the tool-chip partitioning is influenced dramatically by increasing the tool rotational speed at low to moderate levels of tool speed. Also, there is an optimum tool rotational speed at which further increase in the tool rotational speed increases the average tool temperature.

Estimating the Wall Heat Flux of Unsteady Conjugated Forced Convection Between Two Corotating Disks Using an Inverse Solution Scheme

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
David T. W. Lin ◽  
Hung Yi Li ◽  
Wei Mon Yan
Keyword(s):  
Heat Flux ◽  
Forced Convection ◽  
Boundary Surface ◽  
Temperature Sensors ◽  
Inverse Solution ◽  
Wall Heat Flux ◽  
Unknown Boundary ◽  
Measured Temperature ◽  
Solution Scheme ◽  
Good Agreement

An inverse solution scheme based on the conjugate gradient method with the minimization of the object function is presented for estimating the unknown wall heat flux of conjugated forced convection flows between two corotating disks from temperature measurements acquired within the flow field. The validity of the proposed approach is demonstrated via the estimation of three time- and space-dependent heat flux profiles. A good agreement is observed between the estimated results and the exact solution in every case. In general, the accuracy of the estimated results is found to improve as the temperature sensors are moved closer to the unknown boundary surface and the error in the measured temperature data is reduced.

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