next class: text

Next Class: Text

1.5 hour long- Bee in class at 12:20 pm

Open book, open notes

- Comprehensive

Next week (Monday at 10-12) extra office hours related to the Test

Objectives

• Finish with Ducts design • Example

• Review for the Exam• Answer your

Frictional Losses

Non-circular Ducts

• Parallel concept to wetted perimeter

Dynamic losses

• Losses associated with• Changes in velocity• Obstructions• Bends• Fittings and transitions

• Two methods

• Equivalent length and loss coefficients

Loss Coefficients 20

1

0

1

VV

CC

»ΔPt = CoPv,0

Electrical Resistance Analogy

Example 18.7

• Determine total pressure drop from 0 to 4

Fan selection

• Calculated DP and V

Fan Performance

Conversion Between Methods

f

DCL

g

VC

gD

VLf

eq

eq

0

2

0

2

22

Se Example 18.8 and compare with 18.7

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

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

Direct Contact (10)

• Purpose of cooling towers

• Psychrometrics

• Describe how a cooling tower works

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

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

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

Diffusers, Duct Components (18)

• Select diffusers• Define all terms on manufacturer data sheets

• Calculate pressure drop of:• Straight duct• Duct fittings

• Differentiate fans and describe fan curves

Duct layout/design (18)

• Equal friction method• Supply or return systems• Balance the system