Comments kceridon has made
- Hmmmmmm. . . I personally think that needs to be modeled. The thermal capacity and thus thermal mass of an empty freezer is lower and no insulation is perfect. Over time, the cold point source (eg the freezer) will equalize in temp with the sink (eg the outside air) even if the door is never opened. The time constants might end up being very similar and the differences inperceptable to a user, but for an empty freezer versus a freezer with some veggies in it that time constant will differ by a factor on the order of what k(air) versus k(veggies) differ. A simple 2D lumped capacitance and energy balance model will show this because water (which is what most of your veggies are made of) have a much higher k and cp. Sorry to get super nerdy on here, but I am what I am.On Ask Umbra on canned and frozen foods posted 1 month ago 23 Responses
- With regards to the efficiency of a freezer. Yes, the frozen vegetables have a high thermal capacitance than air. First, efficiency is not the correct term for this - the performance of your freezer, aka efficiency, is based on the temperature difference between the cold area and the heat sink (eg outside the freezer). The "Carnot efficiency" dictates the maximum efficiency of your fridge given that temperature difference. Energy use is a better term for this discussion. The main thing here is that a set volume of material with higher thermal capacity takes longer to CHANGE temperature and one with lower thermal capacity. To cool a material with higher thermal capacity, it takes more energy. So, to get your veggies to 32F from 65F, it takes more energy than to get the same volume of air to 32F from 65F. The second part is warming the veggies versus the air. The veggie will not warm up as fast as the air. No matter how well a freezer is insulated, if it is off, it will heat up sooner or later. If it is full of veggies, it will take longer to heat up than if it is empty due to the larger thermal capacity. The compressor on a freezer turns on and off in response to the change in temperature, so if your freezer is full of veggies rather than air, it will turn on and off less frequently. If it is full of air it will cool off faster and the on cycle will be shorter. However, the temperature changes really quickly this way and the freezer commonly overshoots is prescribed temperature which is wasteful. All of that said, it is a somewhat complex issue and I have not done the numbers to say which is better, but my gut says, you should have some capacity in your freezer. Besides, what's more of a waste of perfectly good energy than an empty freezer? However, to really improve the performance of your freezer, you are far better off keeping it as far away from your stove/oven and heaters and near the coolest part of your house or kitchen. You should limit the amount of time you open it and set the temperature to the highest tolerable setting - stick an oven thermometer in there if you don't have a temp setting to find a good temp. Also, the same can be said for ovens. Your oven heat air to temps past the set temp so that your food reaches the desired temp. This is why metal pans burn edges of cakes, but that is a story for another day. BTW - Just to establish my cred, I have a master's in cryogenics.On Ask Umbra on canned and frozen foods posted 1 month ago 23 Responses
This makes me ponder what the footprint of selling 1000 books (cradle to grave) is compared having 1000 visitors to a website. Sure, that may not make you as much money, but it is about perspective.
On Umbra advises on web hosting posted 7 months ago 13 ResponsesWhat about their junk
That is interesting considering I have received mountains for junk from both Natural Resources Defense Council and National Wildlife Federation. Considering they are environmental organizations, I have sent numerous complaints about this practice. Who is stopping thier spam? i use 41pounds.org to stop my snail mail spam.On New anti-junk-mail service stops unwanted catalogs for free posted 2 years, 1 month ago 4 Responses