Method for determining Heat Removal Requirements
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| Step1: |
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Collect information and data about a product to be cooled
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Specific heat (J/kg・ ) |
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Weight (kg) |
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Temperature difference ( t)
( actual temperature minus desired temperature ) |
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Cooling time (sec) |
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| Step2: |
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Determine the amount of heat ( per second )to be removed to cool the product (Heat Removal Requirements ) by applying the following formula to the above information.
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| Heat Removal Requirements (W) = |
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Weight (kg)x Specific heat (J/kg・)x Temperature difference (t) |
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| Cooling time (sec) |
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| Step3: |
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Safety ratio and selection of the adequate UCAG model
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| 1) |
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Determine heat removal requirements including various losses (Heat Removal Requirements Including Losses ) based on Heat Removal Requirements obtained in the above Step 2.
In selection of the adequate UCAG model, take into consideration losses ( efficiency 60-80%) derived from shape of the product, distance between the cold end of the UCAG and the product, etc. In case of cooling the product down below the ambient temperature, take into consideration heat which the product absorbs from ambient surrounding.
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All the heat (cold air) from the UCAG cannot be absorbed by the product. |
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Heat Removal Requirements Including Losses = (Heat Removal Requirements of Step 2) / (efficiency (0.6∼0.8))
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| 2) |
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Confirm the available compressed- air pressure and select the adequate model of the UCAG.
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The available compressed- air pressure at the inlet of the UCAG should be confirmed.
( not the compressed- air pressure at the outlet of compressor ) |
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Confirm the air consumption of each model of the UCAG under the each available compressed- air pressure. |
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Example of determining Heat Removal Requirements
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| Step1: |
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Taking an iron product as an example,
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Specific heat of the product = 460 J/kg・ |
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Weight = 1kg |
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Temperature difference (t) = Temperature of the product 50 - Desired temperature 30 = 20 |
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Cooling time = 40sec |
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| Step2: |
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| Heat Removal Requirements (W) = |
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1Kg x 460(J/kg・) x 20 |
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| 40(sec) |
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230(W) |
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| Step3: |
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| 1) |
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Determine Heat Removal Requirements Including Losses based on the above Heat Removal Requirements of Step2, supposing efficiency is 0.7.
Heat Removal Requirements Including Losses =230 (W) / 0.7 = 329 ( W )
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| 2) |
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Select the adequate UCAG model confirming available compressed-air pressure.
For example, with available compressed -air pressure at 0.7Mpa, the UCAG model 190-75SV has a cooling capacity of 343(W).
And, at this time, air consumption is approximately 650 l/m.
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Above Heat Removal Requirements is just a calculated figure. Actually, as various factors including radiation heat have an intricate affect, above calculated figure should be considered only as an index. And there are losses which vary depending on a number of factors, such as distance between the UCAG and the product, size and shape of the product, etc. |
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) on the UCAG model 190-75SV).
