Objectives Finish with compressors Learn about refrigerants and expansion valves (Ch. 4) Start with heat exchangers.

Slides:



Advertisements
Similar presentations
Refrigeration & Air Conditioning
Advertisements

Refrigeration Basics 101 By: Eric Nelson.
Refrigeration Cycles CHAPTER 11: PTT 201/4 THERMODYNAMICS
REFRIGERATION Refrigeration may be defined as the process of removing heat from a substance under controlled conditions and reducing and maintaining the.
100% Outside Air and Dehumidification Management
Moisture to water converter. Out Line : Abstract Introduction Heat Pump Heat Pump Components Conclusion.
Basic Refrigeration Cycle
Refrigeration Flow Control
ROLL NO :3448. What is HVAC ? What is HVAC ? H.V.A.C – Heating, Ventilation and Air Conditioning system A HVAC System consists of a chain of components.
Section 12.4: Phase Changes
Refrigeration and Heat Pump Systems Refrigeration systems: To cool a refrigerated space or to maintain the temperature of a space below that of the surroundings.
ISAT Module III: Building Energy Efficiency
Evaporators For Air Conditioning
Refrigeration Cycles Chapter 11: ERT 206/4 THERMODYNAMICS
Objectives Review thermodynamics
SYSTEM COMPONENTS CHAPTER 5page 91C & 93 L. OBJECTIVES l IDENTIFY AND COMPARE THE STATE OF REFRIGERANT IN EACH SECTION OF A/C SYSTEM. l EXPLAIN PURPOSE.
CHAPTER 6 Moving Heat: Heating and Air Conditioning Principles
Objectives Finished Cooling Towers and Adiabatic Humidifiers
Air-Source Heat Pumps I North Seattle Community College HVAC Program Instructor – Mark T. Weber, M.Ed. Airsource Heat Pump 1.
Objective Heat Exchangers Learn about different types
 Air conditioning Category: 1. Refrigeration cycle 2. Heat pump 3. Evaporative cooling  Refrigerants  Air conditioning system configurations  Refrigeration.
Important variables Water: Air: Conversion:
Lecture Objectives: Finish with HVAC Systems Discuss Final Project.
Objectives Compare real and ideal compression process Learn about expansion valves (Ch. 4) Compare residential and commercial systems Introduce heat exchangers.
Objectives Finish up discussion of cycles Differentiate refrigerants Identify qualities of a good refrigerant Compare compressors Describe expansion valves.
Matter Chapter 2. Chemistry  The study of matter and how it changes  Matter = has mass and takes up space  Simplest form of matter = Atoms  Different.
Refrigeration Basics 101.
Objectives Solve examples Learn about refrigerants, compressors, and expansion valves (Ch. 4) Compare residential and commercial systems Introduce heat.
Vapour Compression Refrigeration Systems
Objectives Learn about refrigerants, compressors, and expansion valves (Ch. 4) Introduce heat exchangers (ch.11)
Chapter One Basic Concepts in Refrigeration Basic Concepts in Refrigration1.
The Refrigeration Process
SAFETY, TOOLS & EQUIPMENT, SHOP PRACTICES
Objectives Finish up discussion of cycles Differentiate refrigerants Identify qualities of a good refrigerant Compare compressors Describe expansion valves.
1 Air Conditioning Refrigerants. 2 Desirable Refrigerant Properties Non-Toxic Non-Flammable Chemically stable Resistance to chemical breakdown Easy to.
Objective Discuss Expansion Valves and Refrigerants Heat Exchangers Learn about different types Define Heat Exchanger Effectiveness (ε)
Section 3.3 Phase Changes.
Objectives Cooling Cycles –Examples Cooling system components Refrigerants.
PRIMARY AND SECONDARY REFRIGERANTS
PHYSICAL, CHEMICAL AND THERMODYNAMIC PROPERTIES OF REFRIGERANTS REFRIGERANT: It is any substance that absorb heat through expansion or vaporization and.
Refrigerants & Coolants Bartosz Zajaczkowski, PhD Lecture 2.
Refrigeration Systems
 Has fixed volume  Has fixed shape  Molecules are held in specific locations  by electrical forces  vibrate about equilibrium positions  Can be.
Prepared by:- B.S.Bhandari Faculty HNBGU.  Refrigeration is a science of producing and maintaining temperature below that of the surrounding temperature.
HVAC Design: Field Trip Wednesday, October 22nd 9 am Location: St
SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering
Section 2: Safety, Tools and Equipment, and Shop Practices
Heat Transfer and Refrigeration Cycle
. Level 3 Air Conditioning Inspections for Buildings
Heat Transfer and Refrigeration Cycle
Refrigeration & air conditioning
Visit for more Learning Resources
Introduction to Food Engineering
High Temperature Reservoir Low Temperature Reservoir
SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering
The Basic Direct Expansion Refrigeration Cycle
Refrigeration Basics By: Mohamed Iqbal Pallipurath.
ICE 101 REFRIGERATION BASICS
Objectives Cooling Cycles Cooling system components Refrigerants
Announcement Rapid and Early Energy Modeling for the Engineers for a Sustainable World Shah Smith and Associates Scott Sevigny Wesley Stidham March 8th,
Objectives Cooling Systems
By: JAGDEEP SANGWAN Refrigeration Basics 101.
Refrigeration and Air Conditioning
Refrigeration and Air Conditioning
Refrigeration & Air conditioning
Air Treatment School Refrigerated Dryer Training
Presentation transcript:

Objectives Finish with compressors Learn about refrigerants and expansion valves (Ch. 4) Start with heat exchangers

Summary Many compressors available ASHRAE Handbook is good source of more detailed information Very large industry

Expansion Valves Throttles the refrigerant from condenser temperature to evaporator temperature Connected to evaporator superheat Increased compressor power consumption Decreased pumping capacity Increased discharge temperature Can do it with a fixed orifice (pressure reducing device), but does not guarantee evaporator pressure

Thermostatic Expansion Valve (TXV) Variable refrigerant flow to maintain desired superheat

AEV Maintains constant evaporator pressure by increasing flow as load decreases

Summary Expansion valves make a big difference in refrigeration system performance Trade-offs Cost, refrigerant amount Complexity/moving parts

Refrigerants

What are desirable properties of refrigerants? Pressure and boiling point Critical temperature Latent heat of vaporization Heat transfer properties Viscosity Stability

In Addition…. Toxicity Flammability Ozone-depletion Greenhouse potential Cost Leak detection Oil solubility Water solubility

Refrigerants What does R-12 mean? ASHRAE classifications From right to left ← # fluorine atoms # hydrogen atoms +1 # C atoms – 1 (omit if zero) # C=C double bonds (omit if zero) B at end means bromine instead of chlorine a or b at end means different isomer

Refrigerant Conventions Mixtures show mass fractions Zeotropic mixtures Change composition/saturation temperature as they change phase at a constant pressure Azeotropic mixtures Behaves as a monolithic substance Composition stays same as phase changes

Inorganic Refrigerants Ammonia (R717) Boiling point Critical temp = 271 °F Freezing temp = -108 °F Latent heat of vaporization Small compressors Excellent heat transfer capabilities Not particularly flammable But…

Carbon Dioxide (R744) Cheap, non-toxic, non-flammable Critical temp? Huge operating pressures

Water (R718) Two main disadvantages? ASHRAE Handbook of Fundamentals Ch. 20

Water in refrigerant Water + Halocarbon Refrigerant = (strong) acids or bases Corrosion Solubility Free water freezes on expansion valves Use a dryer (desiccant) Keep the system dry during installation/maintenance

Oil Miscible refrigerants High enough velocity to limit deposition Especially in evaporator Immiscible refrigerants Use a separator to keep oil contained in compressor Intermediate

The Moral of the Story No ideal refrigerants Always compromising on one or more criteria

Heat Exchangers

Systems: residential Indoor Air Outdoor Air

Large building system Chiller

Outdoor air 53 o F 43 o F Water to building Water from building 95 o F

Air-liquid Tube heat exchanger Plate heat exchanger Heat exchangers Air-air

Some Heat Exchanger Facts All of the energy that leaves the hot fluid enters the cold fluid If a heat exchanger surface is not below the dew point of the air, you will not get any dehumidification Water takes time to drain off of the coil Heat exchanger effectivness varies greatly

Heat Exchanger Effectivness (ε) C=mc p Location BLocation A T Hout T Cin T Cout T Hin Mass flow rateSpecific capacity of fluid

Example: What is the saving with the residential heat recovery system? Furnace 72ºF 32ºF 72ºF Outdoor Air For ε=0.5 and if mass flow rate for outdoor and exhaust air are the same 50% of heating energy for ventilation is recovered! For ε=1 → free ventilation! (or maybe not) 52ºF Exhaust Gas Combustion products Fresh Air