Turbine Hall CFD Study: Evaluating Ventilation Impact on Temperature and Humidity

Description

Turbine Hall CFD Study

Project Description:

In this project, a turbine hall ventilation is simulated. The study aims to investigate thermal conditions, including temperature and relative humidity, in the summer. The turbine hall is located in Hong Kong. Based on the data, we`ve considered the average values: temperature 34Celcius degrees, RH 75% for the ambient.

CFD Simulation:

For turbine Hall, the pressure-based solver is employed due to the incompressibility of the fluids. The gravitational acceleration is considered. Plus, to measure relative humidity, the species transport model is used. So, the fluid domain consists of a mixture of Nitrogen, water vapor and oxygen.

It is worth noting that, although the fluid domain is huge and may increase computational costs by increasing mesh cells, the boundary layer is generated near the walls to prevent any probable error. All in all, about 3 million tetrahedron elements were generated.

In addition, six 1.5*1.5m exhaust fans were placed on the roof with 8 meters distance between them.

Results:

There are four scenarios. To get a general view of how the ventilation condition is, we need to take a look at temperature and velocity contours on section planes in different coordinates of the turbine hall. In the figures below, the temperature & velocity field distribution in Scenario #1 is depicted. As you can see, because of natural ventilation, the temperature differs at different levels. The higher the level, the warmer it gets. So, it is not fair and practical to investigate the thermal condition by volume average temperature. To overcome this problem, we`ve decided to monitor temperature at different levels to have an XY chart. This will be discussed in the following.

As mentioned above, we`ve created 4 lines to control the temperature field on them, shown below. One of them is on top of the platform, and the rest are on the hall`s floor. (Check the figure below)

After that, we were able to plot temperature over different heights for all scenarios as shown below.

The plots show that the worst-case scenario takes place in Scenario #1, where the doors are closed and the unit status is onloading. Thus, the temperature even reaches 40 degrees Celsius at 25 meters above the floor. Fortunately, there is no worker there and it cannot cause any serious problem. Still, the temperature around the floor and up to 5 meters above is around 35 – 36 degrees Celsius. It gets worse than that on the platform. Thus, it is suggested not to close the doors while the unit status is onloading. By just opening the inlet doors (Scenario #2), the ambient temperature dominates the whole turbine hall, which is an improvement in thermal conditions. In this condition, most of the important working areas have 34 degrees Celsius or so. On the other hand, when the unit status is offloading, actually it doesn`t really matter whether to open the doors or close them (Scenario #3 #4). It is safe for the workers because the temperature remains below 34.5 degrees Celsius.

In the end, the relative humidity of the hall is summarized in the table below: