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| Reviewed: |
Apr 29, 2009 by Engineering Editorial Board |
| Overview: |
This online calculator predicts heat transfer from air natural convection
rectangular heat sinks, typically for electronic equipment. The calculator
allows for both single and back-to-back configurations. It includes uniform and
non-uniform fin temperature cases. The user specifies certain geometric
characteristics, contact conductance and ambient temperature. Constant base
temperature or constant heat flux problems can be solved. The calculator offers
additional technical information about the results, such as dimensionless
numbers, heat transfer coefficient or fin efficiency.
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| Learning Goals: |
To obtain a better understanding of fin arrays used as heat sinks for
electronics and other applications.
Students will be able to evaluate real heat sinks performance as a function of geometric and boundary conditions. |
| Target Student Population: |
Junior/senior college students majoring in mechanical engineering or a closely
related field.
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| Prerequisite Knowledge or Skills: |
A good working knowledge of heat transfer fundamentals and theoretical heat
sinks performance is required, specifically understanding of convection heat
transfer from parallel plate channels.
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| Type of Material: |
Simulation applet.
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| Recommended Uses: |
Classroom demonstration or tool to form basis for homework assignments.
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| Technical Requirements: |
Browser capable of supporting Javascript applets.
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| Strengths: |
The calculator deals with the problem of heat transfer in extended surfaces,
and is consistent with todays engineering heat transfer textbooks.
The case study of rectangular heat sinks in natural convection provides useful
data for further analysis and understanding of heat sinks performance. In
particular, it could be used to show the influence of geometric factors (fin
length, fin thickness fin spacing, etc.) and boundary conditions (source
temperature, heat flux, ambient temperature).
The content is up-to-date and consistent with the current engineering
practice, such as the use of Rayleigh and Nusselt dimensionless numbers, the fin
efficiency concept or the heat transfer coefficient.
The accuracy of the results is quite good when the calculator is compared with
data and examples cited in the specialised literature in this area.
The calculator certainly helps in removing much of the effort involved in the
calculation of heat transfer problems.
The content and results from this calculator can be useful as previous
knowledge in advanced heat transfer courses, such as design of heat sinks or
thermal modelling of electronic components, for example.
All functions and properties are in SI units.
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| Concerns: |
There is no data about the material the heat sink is made of (it seems to be
aluminium). In the same sense, there is no possibility of evaluate the influence
of different materials (thermal conductivity) in non-uniform fin temperature
cases.
The ambient and source temperature are limited between -75ºC and 125ºC. This
range is valid for the air temperature in many applications, but the source
temperature range limits the calculator applicability to typical microelectronic
cooling problems,
reducing its potential value in other fields (mechanical or
aeronautic engineering)
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Potential Effectiveness as a Teaching Tool |
Rating:     |
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| Strengths: |
The calculator could be effective as a teaching tool:
o If it is used by the teacher in the classroom, solving problems during the
lectures.
o If it is used by the students to solve or validate homework problems.
In both cases the solution to heat sinks problems involves complex equations
that are time-consuming to solve. The calculator provides almost instantaneous
solutions
As a result, with small and progressive changes in the influence variables,
heat transfer performance of rectangular heat sinks can be obtained. So, the
student main effort can be focused to data analysis.
The "Details" button is a particularly useful feature. It brings up an entire screen of pertinent information that includes the air properties assumed and some pertinent dimensional and dimensionless variables.
The learning object makes certain that the user does not specify an array that exceeds the maximum dimensions specified in the beginning of the analysis by the user. This "check" could prove quite useful to beginning students who might be careless with their input. |
| Concerns: |
Each case must be solved separately. To obtain a sufficient number of data for
further analysis (the solution of a single case is of small or none learning
effectiveness), several cases must be run successively. As no data record
utility is provided, printing results is the only option. That means a lot of
paper to study.
Some theory information function button could be of help to remind the student
the heat transfer equations and relationships involved in the problem solved.
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Ease of Use for Both Students and Faculty |
| Rating: |
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| Strengths: |
The material is very easy to use and quite intuitive. If the user is at all
familiar with fins, using the object should present no difficulty whatsoever.
The various geometric parameters are clearly labeled and the inpout boxes are
located adjacent to the figure.
The functions of all labels and buttons are very clear,
and the results appear
instantly once the "Calculate" button is clicked.
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| Concerns: |
In many cases, the reset function button does not operate correctly.
If the object could handle both SI and English units, it would be even more useful. However, this is not a major shortcoming. |
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| Other Issues and Comments: |
Heat transfer deals with conceptual, non-visual problems. So, the students
engagement (usually through images, videos, etc. in other engineering sciences)
with heat transfer software learning tools is difficult to obtain.
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