Docsity
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Docsity AI
Docsity AI
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search for your university

Find the specific documents for your university's exams

Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

Cooling Systems: Refrigerant Conditions, Components, and Cycles - Prof. Jeffrey A. Siegel, Study notes of Architecture

The University of Texas at AustinArchitecture
Prof. Jeffrey A. Siegel

An overview of cooling systems, focusing on refrigerant conditions and components in different cycles. It covers vapor compression, absorption, and evaporative cooling, discussing their unique features and advantages. Temperature and pressure values, as well as questions related to the operation of expansion valves and refrigerant phases.

Typology: Study notes

Pre 2010

Uploaded on 08/27/2009

koofers-user-ikm
koofers-user-ikm 🇺🇸

9 documents

1 / 8

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Cooling Systems
• Text
• 4.1 – 4.5
• Parts of 4.6
• Describe refrigerant conditions and
components in different cycles
92 °F
56 °F
69 psig
DB = 77 °F
WB = 64 °F
orifice
capillary tube
TXV
110 °F
~200 psig
DB = 60 °F
WB = 53
°F
High pressure, high boiling/condensing point
Low pressure, low boiling point
pf3
pf4
pf5
pf8

Partial preview of the text

Download Cooling Systems: Refrigerant Conditions, Components, and Cycles - Prof. Jeffrey A. Siegel and more Study notes Architecture in PDF only on Docsity!

Cooling Systems

  • Text
    • 4.1 – 4.
    • Parts of 4.
  • Describe refrigerant conditions and

components in different cycles

92 °F 56 °F 69 psig DB = 77 °F WB = 64 °F orifice capillary tube TXV 110 °F ~200 psig DB = 60 °F WB = 53 °F High pressure, high boiling/condensing point Low pressure, low boiling point

The purpose of an expansion valve in a vapor

compression cycle is to ________.

A) Lower refrigerant pressure before entering evaporator B) Lower refrigerant pressure after leaving evaporator C) Raise refrigerant pressure before entering evaporator D) Raise refrigerant pressure after leaving evaporator Why is it desirable to have lower pressure in the evaporator?

A. Lowers the boiling point of refrigerant

B. Raises the boiling point of refrigerant

C. Lowers the pressure drop

D. Raises the density of the refrigerant

Evaporative Cooling

  • Wet media/water spray – direct
    • Raise absolute humidity, lowers temperature of conditioned air
  • Cooling tower – indirect
    • Cools through a heat exchanger
    • Lowers temperature around condenser (outside)
    • Does not affect indoor absolute humidity
    • Can directly cool air in cold weather

Why Chilled Water?

  • Big centralized equipment
    • Low noise
    • Access to cooling towers
    • Easier maintenance
      • Less chance of leak
  • Easier to make changes/add buildings
  • Small pipes for distribution

Disadvantages of Chilled Water?

  • Water freezing
  • Water treatment
  • No condensing pump
  • Bigger first cost

What about phase change?

  • Common problem, sizing an evaporator coil
  • How cold should an evaporator coil be?
    • Too cold and water will freeze out of air
    • Too warm and it won’t dehumidify
  • Relevant equation
    • q= ρ ×Q×(^ hfg + C× ΔT )
    • Often have to solve for both air and for refrigerant
    • Often have to do mass balance on water/water vapor

Example

  • Size an evaporator coil that will cool 1000 CFM of air from 85 °F and 50% RH to 60 °F
  • Coil temperature is 40 °F everywhere in coil
  • Refrigerant is R-22 and is just boiling everywhere in coil
  • What is sensible capacity of coil?
  • What is latent capacity of coil?
  • What is total capacity of coil?
  • How much water is removed by the AC system?
  • What is refrigerant mass flow rate?
  • What is volumetric flow rate of refrigerant into coil?
  • What is volumetric flow rate of refrigerant out of coil?