Thanks Jim.
I tried the OtherEquipment route before. What I found is that the room gets too cool. My gut feeling is that there is an "efficiency" factor on the evaporative cooling effect that needs to be applied so that the room temperature can be "reasonably" cool. I was just lost trying to determine the efficiency factor.
Any thoughts?
Ery
On 01/07/2012 08:23 AM, Jim Dirkes wrote:
Dear Ery,
It sounds as though you want to consider the evaporation from the pool surface as an evaporative cooler. I trust that you have determined the rate of evaporation already and now need to apply that to the space.
Since the evaporation rate in pounds / kg of water per hour is known, you also know the equivalent sensible cooling rate (roughly 1000 BTU / pound of water). Armed with this information on an hourly basis, two possible strategies come to mind:
1. Define a water cooling coil which mimics your evaporative cooling effect. (This looks messy because there is no apparent way to directly control the cooling capacity and you will also need to define a chilled water loop and delete it’s energy from your totals.)
2. I think past posts have noted that you can define objects such as OtherEquipment with a negative energy value (i.e., cooling). If you also define a fractional schedule that mimics your evaporation rate, you should get the temperature effect represented properly.
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Ery Djunaedy
Sent: Saturday, January 07, 2012 2:20 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Outdoor swimming pool
A question and some thoughts on this topic.
I developed a similar method as Jim described below, but for the purpose of my simulation, this is not enough. The method is used primarily to design a heating system for the pool. My problem is totally the opposite: an indoor swimming pool in the tropics. The swimming pool is inside a semi-enclosed naturally ventilated space. Water heating is not required, as it is assumed that the water is constantly replenished with the right temperature.
The method below will calculate the evaporation rate, which will become the latent heat for the space. This is pretty straight forward as Jim mentioned, but it does not give any free sensible cooling to the room. The crux of the problem that I want to achieve is how to calculate the free cooling from the water. So here is what is missing from this method:
1. Convection heat to/from the pool. The air temperature is higher than the water temperature, so the room should be cooled some what.
2. On the evaporation rate calculation, the method assumes that all of the heat to evaporate the water is coming from the water, i.e. the reduction in water temperature. As this evaporation happens in the surface, should not some of the heat come from the air, i.e. there should be a reduction in the air temperature?
Any thoughts on how to estimate the values of this two? And how to do it in EnergyPlus?
Ery
On 11/29/2011 12:16 PM, jvd2pe wrote:
Dear Forum,
I need to model the energy use of a heated OUTDOOR swimming pool. I have "invented" a method using Shah method calculations for an indoor pool and modifying the evaporation rate for the outdoor conditions instead of indoor. (some psychrometric calcs plus a Schedule:File object)
After doing so and assessing its weaknesses (e.g., it does not account for wind speed), it occurred to me that one of you may have already done something for an outdoor pool and would be able to critique my method.
Hoping for some collaborative help on this one! Thanks in advance.
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