Lab Assignment #5 – Duct Design Project
(Undergraduates: 50 HW points. Graduates: 70 HW points).
All. Use CFD to design air conditioning ducting to provide air from a special A/C unit Outlet (36”x36”) to Outlets #1,2 and 3, shown in Figure 1, serving several spaces in a hospital building. For Outlet #1, the required flow rate is 2000 cfm, Outlet #2 requires 1500 cfm and Outlet #3 requires 1000 cfm. Size the ducting to provide air to various outlet locations. From the CFD results determine the A/C fan static pressure that is required for this application. The elevation view is shown in Figure 2. The outlet ducts must run to an elevation of 1” above the suspended ceiling to allow A/C outlet to be installed.
Graduate Students Additionally Do #1 or #2 below.
#1. Assume the A/C unit outlet temperature is 40 F, use CFD and add
(a) heat flux to the ducting walls or
(b) add hot air to each branch from a furnace
to provide a temperature of 55 F in Outlet #1, and 80 F in Outlets #2 and #3. Determine
(a) the required heat flux at the boundaries or
(b) how/where you can provide the hot air (what is the quantity and temp of hot air required) and also determine if this will cause a change in the outlet flow rate of the A/C unit and the required static pressure of the A/C fan.
#2. Without changing the size of your duct system design, provide internal parts/baffles to modify the flow rates so that for Outlet #1 be 1500 cfm, Outlet #2 provide 500 cfm and outlet #3 provide 2500 cfm. From the CFD results determine the A/C fan static pressure that is required for this application.
Both Undergraduates and Graduate Students: Provide a short report summarizing your design, findings and the required information. Discuss shortcomings of your design if any.
Figure 1. Top View of A/C and Outlets Locations.
(Dimensions in ft)
Figure 2. Elevation View of A/C Unit and Suspended Ceiling
HVAC DUCT Design Project Grading
- Geometry creation 15 pts.
- Grid generation 5 pts.
- CFD results and post processing 15 pts.
- Design changes if needed for providing required flow
- Presentation of results 15 pts.
- Presentation of HW Results:
- Problem description,
- Preliminary Analysis, your design philosophy
- Duct design geometry presentation (make sure reader can understand the duct design geometry). All Figures in HW must have a title and you must refer to them in your discussions.
- Presentation of Mesh
- Presentation of Sample CFD results
- Report mass flux output from each outlet in tabulated form (and from CFD code in the appendix. Output numbers directly from CFD code in the Appendix). Also report static pressure loss (needed to select a fan for this HVAC duct.)
- Design changes if needed to provide required flow rate
- Appendix: CFD input/output
Additional Work for Graduate Students (20 points):
Report proposed modification to the ducting systems to obtain the required flow rates.
Clearly identify modifications and see number 6 above
heat exchanger design to accommodate temperature output required.
Report proposed heat exchanger design to accommodate temperature output required.
Location of heat exchangers, How they affect required flow rate and static pressure?
How you incorporate heat exchanger into CFD results