Update on Trailblazer Lid changes

Submitted: Wednesday, Sep 29, 2004 at 18:02
ThreadID: 16654 Views:2479 Replies:1 FollowUps:4
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Well I have finally got there!

These are the figures measured for the RC Special lid and Moded lid.
=====================================================
Conditions:
Unit placed on the floor of Trakka Oztent,Flaps closed.
Thermostat setting #5
5kgs of ice as load.
Coat = 20mm ccf (snug fit over the outside)
a) RC =lid + coat + al foil
b) Mod =lid + coat

Calculations were made for ambient temperatures>30c (maximum temperature recorded was 47c)
=====================================================
Result:
RC Special : Duty cycle 42%
Moded : Duty cycle 32%

Temperature measured at the top of the cavity, central
------------------------------------------------------
Ambient Temp MODmax MODmin RCmax RCmin
30 2.0 -3.1 9.1 6.2
35 2.4 -2.8 9.4 6.8
40 2.6 -2.2 10 7.4
45 3.1 -1.4 12.5 9.6

Note: I discarded the cavity fan.The downside of using the coat is that it must be put on in the morning and removed in the late afternoon (the thermal capacity catches up with it!)
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Reply By: Moose - Thursday, Sep 30, 2004 at 13:19

Thursday, Sep 30, 2004 at 13:19
Wok
Sorry mate no idea what that jumble of numbers means. Please explain in simple language what the improvements in performance, if any, were. Is the end result less draw from the battery? The coat you speak of - I assume that is that just for the lid? Because doesn't one have to leave air space around the outside of the fridge?
AnswerID: 78341

Follow Up By: Wok - Thursday, Sep 30, 2004 at 14:57

Thursday, Sep 30, 2004 at 14:57
Sorry Moose!...lost the tabbing

Temperature measured at the top of the cavity, central
------------------------------------------------------
Ambient Temp MODmax MODmin RCmax RCmin
30 2.0 -3.1 9.1 6.2
35 2.4 -2.8 9.4 6.8
40 2.6 -2.2 10 7.4
45 3.1 -1.4 12.5 9.6

The improvements are two fold,
1. There is less Ah used, about 24%
2. The cavity is food safe to the top ( taking 4c as the upper limit)

Yes, the coat only covers the lid.

From the table I would estimate that the RC (with coat) has an upper limit between 40c & 45c.Plot the Table, you will see what I mean.

IMHO opinion, a good product is now better.Hope this helps.
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FollowupID: 337901

Follow Up By: Wok - Thursday, Sep 30, 2004 at 15:02

Thursday, Sep 30, 2004 at 15:02
TRY AGAIN!

Temperature measured at the top of the cavity, central
------------------------------------------------------
Ambient Temp MODmax MODmin RCmax RCmin
30 ...................2.0 ........-3.1 .......9.1 ......6.2
35 ...................2.4 ........-2.8 .......9.4 ......6.8
40 ...................2.6 ........-2.2 .......10 .......7.4
45 ...................3.1 ........-1.4 .......12.5 ....9.6
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FollowupID: 337902

Follow Up By: Moose - Thursday, Sep 30, 2004 at 15:21

Thursday, Sep 30, 2004 at 15:21
Wok
I'm really interested in your work here but please bear with me - I'm not particularly cluey when it come to technical stuff relating to fridges.
Please clarify:
top of cavity = just under the lid?
MOD = standard fridge with the "coat" you designed? If not what.
RC = you appear to have introduced alfoil but the results are worse???

Do you have the numbers for a non modified fridge?

If the thermostat setting was a constant 5 why is it that the minimum temps vary - doesn't a thermostat always bring the temp down to the same level irrespective of outside conditions? I assumed the fridge would just run for longer until the temp setting for 5 was reached.

In the previous posts I think you did something to the bottom of the lid ie inside the fridge - please clarify what was done.

You say a 24% reduction in amp hours used - is that simply a factor of less "cold escaping" thus the fridge cycles few times over a given period?

Re the coat - what is ccf?

I know I've asked a heap of questions that to you may well appear dumb but as I said my knowledge of refrigeration is bugger all. I hope you don't mind too much.
Thanks
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FollowupID: 337904

Follow Up By: Wok - Thursday, Sep 30, 2004 at 16:51

Thursday, Sep 30, 2004 at 16:51
top of cavity = just under the lid?
>>>yes

MOD = standard fridge with the "coat" you designed? If not what.
>>>modified lid + coat

RC = you appear to have introduced alfoil but the results are worse???
>>>no, the result is better,the alfoil reduces the radiant energy

Do you have the numbers for a non modified fridge?
>>>yes,I have the figures for the original fridge-lid, there is no significant difference between the RC and the my original.

If the thermostat setting was a constant 5 why is it that the minimum temps vary - doesn't a thermostat always bring the temp down to the same level irrespective of outside conditions? I assumed the fridge would just run for longer until the temp setting for 5 was reached
>>>yes, the switching temperature is unchanged, there is a thermal gradient from top to bottom of the fridge.In my unit the pickup for the thermometeris half way up, it indicates -10c on turn-off.The cooling unit is good, it takes about 30minutes to cool down once stabilised.

In the previous posts I think you did something to the bottom of the lid ie inside the fridge - please clarify what was done
>>>the current moded lid
1. alloy inner shell discarded
2. polyurethane block replaced with 40mm Armaflex ( I had an accident with the polyurethane)
3. a piece of corrugated polycarbonate (Danpalon type) 'replaces' the alloy. This is a food-safe product as it is exposed to the cavity.

You say a 24% reduction in amp hours used - is that simply a factor of less "cold escaping" thus the fridge cycles few times over a given period
>>>yes, exactly!

Re the coat - what is ccf?
>>>closed cell foam

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FollowupID: 337923

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