Fun and Games with a data logger

markjass · Post by **markjass** » Mon Jun 24, 2013 13:31

While waiting for a few odds and sods to put my curing chambe together I decided to have a bit of fun.

Having a bit of fun. I have been given a temperature and humidity data logger.

Aim: Is to find out if I can use an aquarium heater in a water and salt bath as a method of creating a humidifier in a curing chamber. Not robust - far from scientific.

So far
Within the last 72 hours hours it has been in my lounge, Garage and garden, chilli bin with water salt and an aquarium heater set at 30 degrees (moved it about so it has had closeish blocks of time in all areas.
T = temperature
RH =Relative humidity
About 22.00 hrs
Lounge T 21.9 C R.H. 54.4
Garage T 9.2 C R.H. 71.8
Garden T -2 C R. R.H 100
Chilli bin (with a 300 W aquarium heater set at ) at 30 degrees T 22 RH 100
I had a sausage skin full of sand hanging in each environment. In the chilli bin the sausage skin was totally covered in large droplets of water and the water was dripping. I assume this was in part due to a lack of air flow and the lack of a fine mist.
The chilli bin had the smallest standard deviation.
Thoughts ahah. Will the large beads of water cause a problem with fermentation and curing.

ssorllih · Post by **ssorllih** » Mon Jun 24, 2013 13:54

@100%RH you are getting condensate on the sausage casing.

markjass · Post by **markjass** » Mon Jun 24, 2013 14:06

The only place I have got condonsation on is in the chilli bin.

ssorllih · Post by **ssorllih** » Mon Jun 24, 2013 14:32

All of the other places were at least 9 degrees cooler so the sausage was also cooler.

el Ducko · Post by **el Ducko** » Tue Jun 25, 2013 15:03

Yup, air flow is the key, here. Try allowing some air flow through the whole system. Otherwise, the parts at 100% relative humidity (plus some evaporative potential) will force the whole system to go to 100%.

markjass · Post by **markjass** » Wed Jun 26, 2013 11:34

This is a graph of the raw data from my data logger. The fridge has nothing in it and was not opened during the data recording.

The fridge is in my garage. The temperature on the fridge was set to the max. It is interesting to not the huge range of both peramaters.

Recordings were made every 2 seconds.

ssorllih · Post by **ssorllih** » Wed Jun 26, 2013 12:16

Note that each dip in RH corresponds to a peak in the temperature.

Chuckwagon · Post by **Chuckwagon** » Wed Jun 26, 2013 12:50

The quack Duckaroo said...

Yup, air flow is the key, here.

Now, if there's one person who certainly knows his "air flow", it is El QuackO! The man knows all about passing air, especially if the temperature is elevated!

el Ducko · Post by **el Ducko** » Wed Jun 26, 2013 19:58

ssorllih wrote:Note that each dip in RH corresponds to a peak in the temperature.

...consistent with no air flow.

markjass · Post by **markjass** » Thu Jun 27, 2013 01:06

I think that I will need to install a fan in my chamber. I found this quote online "On the other hand,relative humidity(which is different from absolute humidity)decreases with a rise in temperature.Because,the relative humidity depends not only upon the amount of water vapour actually present but also on the air temperature.Hence,if no moisture is added,an increase in temperature will result in a corresponding decrease in the relative humidity". Could this describe what is happening?

This next graph shows what happenend when the fridge was off and the humidity and heat were generated from a aquarium heater in a tub of saline water was used. The heater is a 300 watt one and has been turned to its lowest setting which is 20 degrees.

The temperature in my guarage would have been about 6 degrees overnight and a relative humidity of 80%. As the fridge is a close unit and was not opened overnight it should not have had an influence.

It will be interesting to see what happens when I get the control unit. Plug the fridge in the heat source and the heater in the humidity socket.

el Ducko · Post by **el Ducko** » Thu Jun 27, 2013 15:08

markjass wrote:I think that I will need to install a fan in my chamber. I found this quote online "On the other hand,relative humidity(which is different from absolute humidity)decreases with a rise in temperature.Because,the relative humidity depends not only upon the amount of water vapour actually present but also on the air temperature.Hence,if no moisture is added,an increase in temperature will result in a corresponding decrease in the relative humidity". Could this describe what is happening?

Yes, that describes it. In a closed system (liquid water reservoir not in the system, water vapor only), the amount of water is fixed. If you vary the temperature, however, the ability of the air to absorb more water vapor changes. Since there's no water coming in, though, the relative humidity (relative to what MIGHT occur, but can't) decreases. The air could hold more water, if water were available, but it's not available.

If you install a fan in a closed system, it won't change the amount of water trapped inside the refrigerator, so nothing will change. (Practically speaking, there'll be some temperature rise due to the energy expended by the fan, but it's small.) Cut a pair of openings and install a fan in one, however, and now the amount of water WILL change. Water flow consists of inward flow (incoming air's water content) plus (if you move the water reservoir inside and heat it with the aquarium heater) the amount evaporated by the heater, minus the water flow outward. Air flow will be air in minus air out. NOW you can control both relative and absolute humidity.

The idea behind the salt/water business is that there is an equilibrium between rock salt and water, and that you can hold humidity somewhat constant by utilizing that property. It's tricky, though, because you can easily overwhelm its effect with air flow. Give it a shot, using a small-flow system, and see how it looks. We did something similar with rock salt and water during the "Project B" days, and to be honest, the results weren't very good when compared with the guys who had decent temperature/humidity control systems. ...but it works, kinda-sorta. (Note that solid salt is present, not just salt water.)

...clear as mud, huh? Well, mud contains water, and...