Objectives Learn about Fans Discuss: Exam (I will have an extra office hour on Monday at 8:00 am) Final Project (I need your group member lists till tomorrow).

Centrifugal fans

Axial Fans

Fan Laws “Approximate relationships” Given two aerodynamically similar fans, can extrapolate performance data Be very careful

Question How does fan power consumption vary with volumetric air flow rate?

Controlling Air Flow

Dampers

Effect on Fan Curve

VAV Operation

Summary of Air Distribution Systems Select diffuser based on ADPI Given a layout of duct system Calculate total pressure drop Identify fittings Deal with non-circular ducts Use fitting loss coefficient or equal length method Select the fan based on fan and duct curve

Review for the Exam Should be able to do all calculations associated with lectures as well as HW1 Questions/problems may deal with context i.e. –Explain how thermal conductivity influences fin efficiency? –How outdoor temperature affect COP –…..

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 Know how the process looks like for different systems Use Psychrometric chart for designing components

Direct Contact (10) Describe how a cooling tower works Describe how evaporative cooling works and know how to do calculation

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 Contrast different refrigerants List important parameters for refrigerant selection/differentiation

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

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

Duct layout/design (18) Describe static regain method Compare to equal friction method Supply or return systems Balance the system

Project Design problem Given cooling and heating load design HVAC for the specific building You will design an HVAC system for a single building Select and size components for VAV or DOAS Select diffusers and design a duct system