STP Team End of Semester Report
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Transcript of STP Team End of Semester Report
Members:Ryan Bigelow, MEEN SrAdam Tallman, CVEN SoIris Hill, ISEN SoAndrew Ingram, MEEL FrRicky Palacios, CHEL Fr
Graduate Mentor:James Hardy, MEEN
Model DescriptionModeling AssumptionsModel ValidationAnalytical ResultsRecommendations
This semester attention was focused on simplifying the previous model, and expanding the model to the entire floor.
CFD efforts were focused on prioritizing techniques used to remove thermal energy from critical rooms on the floor.
Model of floor 0 in SolidWorks Floor 0 modeled as one part Accurate dimensions per STP data
Each room contains: A centrally located heat block that uses
a specific heat generation rate provided by STP
Figure 1. “Floor 0” Model of EAB Building
Can we describe here each room where we have a heat source?How about showing the block where the heat source is applied?
We need to describe here our modeling approach-what is included in our model ( all rooms and corridors?-where are the heat sources-are there any fans to bring in external air?
Overall, this is a good picture to use to explain our modeling approach
Penetration room
Simulations were performed using various door and fan configurations to investigate the effect on room temperature.
A parametric analysis was carried out to determine the variables that had the greatest effect on room temperature.
Model assumptions were tested against results of the parametric analysis to produce a more accurate simulation.
Various assumptions were made in the following areas: Adiabatic Wall Boundary Conditions Heat Source Location and Size Equipment Volumes Fan Specifications
Walls, Floor & Ceiling Adiabatic walls (no heat loss through the
internal/external walls, ceiling, and floors)
Frictionless walls
Penetration Room (adjacent to EAB room) Ambient pressure & 68˚F
Each heat source is modeled as a block that has a total surface area of 1 m2 on the five surfaces that have contact with the fluid
Each heat source is centrally located within each room
CFD model from last semester included thermal mass from equipment in SGR.
Time to reach critical temperature was found to be 22.5 minutes.
The door lids were shut in the SGR and a 85700W heat load was applied to the room to mimic conditions of last semester’s model
This semester, CFD model did not include thermal mass from equipment.
Time to reach critical temperature was found to be 10.5 minutes
Switch Gear Room Analytical Approach - Expected time to reach
104F
CFD Results - Time for model to reach tcrit: 10.5 min Difference between CFD and analytical : 3%
Spring 2009 Tc: 22.5 minutes Fall 2009 Tc: 10.5 minutes
Percent Difference: 53%
Case 1 – “Sealed Floor” Model. No air flow in from penetration room (PR) or flow out from stairwells. All internal doors open, no fans active.
Case 2 – “Sealed Floor” Model. No air flow in from PR or flow out from stairwells. All internal doors open, 6 fans with 6000CFM flow rate placed as per STP procedure.
Case 3 – Air flow is introduced into the EAB from the PR by assigning the PR lid a volumetric flow rate of 6000CFM. All internal doors open, 6 fans with 6000CFM flow rate placed as per STP procedure.
Case 4 – Air flow is introduced into the EAB from the PR by assigning the PR lid a ambient pressure, 68°F boundary. A 6000CFM fan was placed directly in front of lid to provide flow. All internal doors open, 6 fans with 6000CFM flow rate placed as per STP procedure.
Case 5 – Same as Case 4 with additional 6000CFM fan added at Switchgear Room (SGR) doorway. Fan blows air from hallway into SGR.
Case 6 – Same as Case 5, all fans now have 15,000CFM flow rates. Case 7 – Same as Case 6, additional 15,000CFM fan added to SGR at other
doorway. Fan blows air from SGR to hallway.
Initial conditions: All air is at initial temperature of 64°F
No penetration room air flow in
Case 1 – no fans Case 2 – six identical
fans (6000CFM) placed in model as shown on right.
Case 1- Time to reach 104°F (average room) with no forced circulation (no fans): 8.22 minutes
Case 2- Time to Reach 104°F with six fans configured as per STP procedure: 8.62 minutes
5% Difference
Case 2- ( with fans) From the sealed heat up analysis, the following rooms showed fastest temperature rise
SGR heated up 60% faster than any other room
Room Time to 104° F (min) Heat Load (w) Air Volume (ft3)
Switchgear Room 010 8.62 126,255 69,876
Equipment Room 012A 14.00 7,477 1,836
Equipment Room 012 18.78 1,785 3,876
Distribution Room 007 19.11 15,488 6,660
Case 4 - In second method, lid was assigned ambient pressure and temperature (68°F). A fan was placed directly in front of the lid. Differences were negligible. Second method was used in subsequent tests.
Fan placed in front of lidTime to reach 104°F: 8.66 min
Case 3 - Air flow from penetration room was modeled in two ways. A specified volume flow rate boundary condition was established at the lid as seen in figure below.
Volume flow rate assigned to lidTime to reach 104°F: 8.60 min
Introducing flow from the penetration room did not have great effect on the heat up rate.
Time to reach 104°F with no PR flow: 8.62 min Time to reach 104°F with PR flow: 8.60 min 8.60 minutes is the estimated time to reach
critical temperature with current “Loss of EAB HVAC Response Improvements” document procedures.
It was found that there was minimal air exchange in the SGR
Although not in the current procedure, the team investigated adding a fan to the entrance of the SGR. It was found that the heat up rate was decreased by approximately 15%
Time to 104°F without fan in front of SGR: 8.66 min
Time to 104°F with fan in front of SGR: 10.05 min
Strong correlation was found between air velocity and fluid temperature
Velocity profile of EAB floor with 15,000 cfm fan
Case 6 investigated increasing all fan sizes to 15,000 cfm
Case 5 - Time to reach 104°F with 6,000 cfm fan: 10.05 min
Case 6 - Time to reach 104°F with 15,000 cfm fan: 10.37 min
Increasing fan size reduced heat up rate by 3%
A second fan was added that pulled air from SGR.
Time to 104°F fan in front of SGR: 10.37 min
Time to 104°F with fan in front and at exit of SGR: 11.12 min
Time to reach critical temperature was increased by 7%
Figure on left shows velocity profile with all fans set to 15,000 cfm. Figure on right shows an additional fan added to draw air from
switchgear room.
Current fan placement by STP procedure had minimal effect on SGR heat up rate.
Addition of fans to Switch Gear Room produced greatest effect on heat up rate of critical rooms.
Modeling approach is very conservative. However results can be used to update the safety procedures.
Future work will focus on improving the accuracy of the model Evaluate more case studies Conduct further sensitivity analyses on
parameters Add thermal mass to the rooms.
▪ Accurate equipment volumes and weights are needed
Matt King, STP
Mrs. Lagoudas, SEI
Ernie Kee, STP