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Objectives

Objectives. Select project topics Review for exam Learn about DOAS systems. Final Project. Group 5: Nick Williams Stephen Mathai Kevin Carbonnier Group 6: Marcus Allen Josh Atkins Matt Larson Group 7: Stephen Fridley Shahrukh Gaziani Margaret Lawson. Group 8: Marwa Zaatari

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Objectives

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  1. Objectives • Select project topics • Review for exam • Learn about DOAS systems

  2. Final Project Group 5: Nick WilliamsStephen Mathai Kevin Carbonnier Group 6: Marcus Allen Josh Atkins Matt Larson Group 7: Stephen Fridley Shahrukh Gaziani Margaret Lawson Group 8: Marwa Zaatari Megan Gunther Elena Nirlo Group 9: Gregory Arcangeli Andrew Hoisington Tobias Nilsson Individual projects Wesley Cole Adam Keeling Sami Kolahdoozan Gautam Salhotra Group 1: Heather SmithTommy BealesMatt Leos Group 2: Patrick Gorman Kenny Greaves Matt McCarthy Group 3: Sarah Johnson Jocelyn Citty Neil Woodson Group 4: ZaidArzate Brian Burcham Justin Barrett

  3. Project topics 1) VAV system design • Fresh air requirements and recirculation rate calculation • Selection of zonal and central HVAC components based on cooling and heating load components • For zones: VAV boxes, reheaters, reheater plumbing • For whole system: AHU and components, chiller & cooling tower, boiler, and electric power requirement • Control description – sequence of operation • Heat recovery system and or economizers 2) DOAS system design • Fresh air requirement and split between air and hydronic loads (sensible and latent cooling loads) • Selection of zonal and central HVAC components based on cooling and heating load components • For zones: fan coils and plumbing • For whole system: AHU and components, chiller & cooling tower, boiler, and electric power requirement • Control description – sequence of operation • Heat recovery system and or economizers

  4. Project topics 3) Cooling systems and distribution • Air cooled condenser vs. water cooled condenser (energy performance analysis) • Design of plumbing systems for campus and pumping stations • Control of centralized system • Saving with variable speed pumps 4) Duct Design (in Revit) • - Diffuser selection, design of local and central duct system components • - Spacing issues and difference between round and square ducts • - Difference between manual calculation and calculation by Revit (for a section of the duct system) • - Balancing and fan selection • - Life cycle analysis and optimization (fan power consumption vs. system cost)

  5. Course Exam • This Thursday (April 21) 9:20 am • Same classroom • 1.5-hour exam • Cheat sheets • Questions: all problems • (short but comprehensive)

  6. Course Exam • Next Thursday (April 15) 7 pm • Same classroom (ECJ 7.208) • 2.5-hour exam • Open book open notes • All problem types of questions • (short but comprehensive)

  7. Objectives • Finish the pumps and plumbing systems • Discuss the final project

  8. Review for the Exam • Should be able to do all calculations associated with lectures as well as HWs • Problems may deal with context • i.e. Explain how thermal conductivity influences fin efficiency? Holding all other parameters equal, how important is increasing the thermal conductivity

  9. Psychrometrics and Processes (7 & 8) • Know all parameters and their location/orientation on a psychrometric chart • Be able to look up conversions of parameters on a psychrometric chart and with calculations • Use protractor to calculate SHR and ΔW/Δh • Plot processes on a chart for real buildings • List what is held constant for different processes • Describe processes in AHUs in psychrometric chat

  10. Direct Contact (10) • Purpose of cooling towers • Psychrometrics • Describe how a cooling tower works

  11. Cycles (3), Refrigerants (4) • Describe Carnot cycle and components • Understand constant variables for each component • List, describe, and calculate inefficiencies • Use figures, refrigerant tables and equations for different substances • List important parameters for refrigerant selection/differentiation

  12. Heat Exchangers (11) • Differentiate types • Calculate ε, and UA, etc. • Complete broad analysis • Which m is larger, which Δt is larger? • Within and between heat exchangers

  13. Heat Exchangers (11) • Calculate and compare different thermal resistances • Describe influence of key factors • Integrate different parameters/resistances • Manipulate UA equation • Describe differences for wet and dry heat exchangers

  14. Diffusers, Duct Components (18) • Select diffusers • Define all terms on manufacturer data sheets • Calculate pressure drop of: • Straight duct • Duct fittings • Components (coils, VAV boxes, dampers, etc.) • Differentiate fans and describe fan curves • Use fan laws

  15. Duct layout/design (18) • Equal friction method • Supply or return systems • Balance the system • Describe static regain method • Compare them

  16. Project • Design problem • For example: Given cooling and heating load design HVAC for the building • Research problem • Analysis based problem. For example: • Find the optimum solution for…. • Developed control strategy for… • Life cycle cost analysis for … • ……….

  17. Pumps and Fans • Power law • Types and basic properties • Selection process

  18. DOAS System • www.doas.psu.edu

  19. DOAS with multi-split systems Fresh air?

  20. DOAS fresh air configurations

  21. DOAS fresh air configurations

  22. Cooling and Heating Loads (For Project) Commercial building • Zone orientation

  23. Cooling and Heating Loads (For Project) • Cooling and heating load for each zone and whole building: • Fresh air requirement based on number of occupants: • To provide acceptable IAQ in the building, ventilation • system supply minimal amount of • fresh air is in all spaces (except plenums) • that produce 0.2 ACH.

  24. Cooling Load Calculation • Mostly computer based • Handouts for manual calculation • http://www.ce.utexas.edu/prof/Novoselac/classes/ARE346N/Handouts/heatloss_table_2008.doc • http://www.ce.utexas.edu/prof/Novoselac/classes/ARE346N/Handouts/ASHRAE_%20Gains_Calculation_Tables.doc

  25. Heat Recovery Sensible and Enthalpy wheel

  26. Economizer Economizer (fresh air volume flow rate control) • Controlled device is damper • - Damper for the air • - Valve for the liquids • fresh • air • damper • mixing • recirc. • air • T & RH sensors

  27. Economizer – cooling regime How to control the fresh air volume flow rate? • If TOA < Tset-point → Supply more fresh air than the minimum required • The question is how much? • Open the damper for the fresh air • and compare the Troom with the Tset-point . • Open till you get the Troom = Tset-point • If you have 100% fresh air and your • still need cooling use cooling coil. • What are the priorities: • - Control the dampers and then the cooling coils or • - Control the valves of cooling coil and then the dampers ? • Defend by SEQUENCE OF OERATION • the set of operation which HVAC designer provides to the automatic control engineer • % fresh air • 100% • Minimum for • ventilation

  28. Economizer – cooling regime • Example of SEQUENCE OF OERATIONS: • If TOA < Tset-point open the fresh air damper the maximum position • Then, if Tindoor air < Tset-point start closing the cooling coil valve • If cooling coil valve is closed and T indoor air < Tset-point start closing the damper • till you get T indoor air = T set-point • Other variations are possible

  29. Figure 3 – A desiccant-based cooling system combined with regenerative heat exchanger, vapor compression cooling, and evaporative humidifier (hybrid system). Desiccant wheel

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