Building wet outdoor surfaces
Posted: Wed Aug 19, 2015 1:31 pm -1100
Hi:
I am using WUFI plus to simulate a simple building with wet exterior surfaces (e.g. by rain, by water spraying, etc) in order to measure the evaporative cooling effect. I want to compare the resulting temperatures of the building surfaces and the amounts of water that are evaporated under diverse climatic conditions. The building is free running (no air conditioning).
Ideally I would like to control when and which of the building surfaces are wet. For instance, keeping a constant water layer over the southeast wall in the morning (6:00to 12:00) and over the southwest in the afternoon (12:00 to 18:00), or keep the roof wet during all daytime, etc.
I have been trying to do this in two ways:
1. Using a moisture source at walls and roof (0.00005 kg/s m2 from 6:00 to 18:00). I defined a data file as transient moisture source over: a) one element, at the surface of walls (at 0 mm), b) a whole layer, in a separate thin layer of 1mm in walls (or a thin layer of fictitious absorbing material in the metal roof). I have also tried the moisture sources using "fraction of driving rain".
2. Using a constant rain load: I have changed the original weather data file to keep a constant rain load of 0.1 Lt/m2 h from 6:00 to 18:00, and keep the rain load and absorption coefficients in "1" for all walls and roof.
With the first case I am able to selectively apply additional water over individual building components and control the times by defining day profiles in the data file. However I have not been successful in keeping a RH=100% at the outdoor surfaces of walls and roof. I have tried changes in moisture storage function of the materials, changes in water absorption coefficient, increased the amount of water, etc. I have also tested moisture sources with WUFI Light but the surfaces never reach RH=100%, only when there is a rain event.
In the second case I can easily apply the constant rain load at defined times and see the constant saturation condition at the exterior surfaces (which is the exactly what I want to happen). However, with this option I have to manipulate the rainfall amounts, eliminating the original rainfall data of the climate file; and I cannot apply the rain load selectively over different surfaces at different times (the times are the same for all the surfaces, I just can indicate which surfaces will not absorb this rain load).
I have some questions:
1. Is it possible to do what I want using moisture sources?. I wonder if I misunderstand this concept or if WUFI plus have bugs in this part, because it has certain differences compared to moisture sources in WUFI light.
2. Is it possible to use ".txt" or ".kli" files with rainfall alone as optional climates? in order to keep the original weather data and give additional boundary conditions to the surfaces.
3. If 1 and 2 are not feasible, could you suggest other ways I could try to simulate wet surfaces that I could control.
I will really appreciate your help.
Thank you
I am using WUFI plus to simulate a simple building with wet exterior surfaces (e.g. by rain, by water spraying, etc) in order to measure the evaporative cooling effect. I want to compare the resulting temperatures of the building surfaces and the amounts of water that are evaporated under diverse climatic conditions. The building is free running (no air conditioning).
Ideally I would like to control when and which of the building surfaces are wet. For instance, keeping a constant water layer over the southeast wall in the morning (6:00to 12:00) and over the southwest in the afternoon (12:00 to 18:00), or keep the roof wet during all daytime, etc.
I have been trying to do this in two ways:
1. Using a moisture source at walls and roof (0.00005 kg/s m2 from 6:00 to 18:00). I defined a data file as transient moisture source over: a) one element, at the surface of walls (at 0 mm), b) a whole layer, in a separate thin layer of 1mm in walls (or a thin layer of fictitious absorbing material in the metal roof). I have also tried the moisture sources using "fraction of driving rain".
2. Using a constant rain load: I have changed the original weather data file to keep a constant rain load of 0.1 Lt/m2 h from 6:00 to 18:00, and keep the rain load and absorption coefficients in "1" for all walls and roof.
With the first case I am able to selectively apply additional water over individual building components and control the times by defining day profiles in the data file. However I have not been successful in keeping a RH=100% at the outdoor surfaces of walls and roof. I have tried changes in moisture storage function of the materials, changes in water absorption coefficient, increased the amount of water, etc. I have also tested moisture sources with WUFI Light but the surfaces never reach RH=100%, only when there is a rain event.
In the second case I can easily apply the constant rain load at defined times and see the constant saturation condition at the exterior surfaces (which is the exactly what I want to happen). However, with this option I have to manipulate the rainfall amounts, eliminating the original rainfall data of the climate file; and I cannot apply the rain load selectively over different surfaces at different times (the times are the same for all the surfaces, I just can indicate which surfaces will not absorb this rain load).
I have some questions:
1. Is it possible to do what I want using moisture sources?. I wonder if I misunderstand this concept or if WUFI plus have bugs in this part, because it has certain differences compared to moisture sources in WUFI light.
2. Is it possible to use ".txt" or ".kli" files with rainfall alone as optional climates? in order to keep the original weather data and give additional boundary conditions to the surfaces.
3. If 1 and 2 are not feasible, could you suggest other ways I could try to simulate wet surfaces that I could control.
I will really appreciate your help.
Thank you