Study Case : CFD at factory

We are doing audit for air conditioning for plastic factory. The factory located at Cikarang, 30 km from Jakarta. Thre are two main areas as common factory, working office and huge space to produce plastic bottle. Space for production has dimension as 108m x 18m and floor to ceiling 6 m. Fit for half of football field.

Main task from owner sounds simple, they want air conditioning make room temperature as 24 degree Celcius with humidity ratio between 50–60 %. Current condition reaches 27–29 degree celcius. After doing first measurement, we find two major problem. Oversizing heating coils to adjust humidity and Air flow reduction because of three different filters (static pressure of fan not big enough).
Second problem is more interesting to be explored. We think about powerful tools to analyse airflow and temperature. Computational Fluid Dynamic (lets say CFD) is chosen to be platform for reviewing air flow and temperature profile. CFD as definition by wikipedia (you can googling it anyway).

If it is still complicated to understand, CFD can make profile of temperature and air velocity in one room. Or in more simple words, CFD can calculate temperature every points in room based on theory. We can understand impact of temperature and air speed if those parameters are higher or lower than measurement or design. Indeed improving condition can be done by using this powerful simulation.
Following pictures are simulation results for main factory area. The supply air condition are based on design without heating coils verified by measurements. Supply air speed at diffuser is 4 ms and temperature close to 14 degree Celcius.

Picture number 1 shows that higher level has higher temperature. It is because air flows from ceiling to return air at lower level.
Picture number 2 and 3 show temperature profile under supply air diffuser. Temperature profile is more uniform compared to picture number 1.
Picture number 4 is temperature profile for horizontal area. Room temperature is around 22–24 deg C.

Current air conditioning without heating coil is enough to get desired temperature. Our next task should find best solution. Adjusting control or even resizing heating coils. Heating coil sizing likely common problem for controlling humidity in Indonesia.

The missing point of the model is internal heat gain from machine and people. Twelve machines need to be evaluated for simulation because of heat from hot steels. There are 9–10 people work in factory, so heat from their activity can be neglected.

Our team will develop this study especially combination with energy simulation. This project can be base framework for designing HVAC system at high ceiling building.

Looks promising.