Providing Solutions. Simplifying Regulation.
Principles of Refrigeration
Peter Thomas, P.E., CSP – Resource Compliance, Inc. Providing Solutions. Simplifying Regulation.
What is Refrigeration? Providing Solutions. Simplifying Regulation.
State 1
14.7 psia
212ºF Water Providing Solutions. Simplifying Regulation.
State 2
Compressor
20 psia
228ºF Providing Solutions. Simplifying Regulation.
State 3
2.5 psia
130ºF Providing Solutions. Simplifying Regulation.
State 4
0.12 psia
40ºF Providing Solutions. Simplifying Regulation.
Saturation
• At equilibrium, the rate of evaporation is equal to the rate of condensation. • This mixture is said to be saturated and composed of liquid and vapor. • When saturated, the temperature and pressure of a substance are dependent. Providing Solutions. Simplifying Regulation.
Vapor Compression Cycle Compressor Providing Solutions. Simplifying Regulation.
Vapor Compression Cycle Compressor
Cold Air Out
Heat Exchanger 1
Warm Air In Providing Solutions. Simplifying Regulation.
Vapor Compression Cycle Compressor
Cold Air Out
Heat Exchanger 1
Warm Air In Providing Solutions. Simplifying Regulation.
Vapor Compression Cycle Compressor Cool Ambient Air In Cold Air Out
Heat Exchanger 2 Heat Exchanger 1
Warm Ambient Air Out
Warm Air In Providing Solutions. Simplifying Regulation.
Vapor Compression Cycle Compressor Cool Ambient Air In Cold Air Out
Heat Exchanger 2 Heat Exchanger 1
Expansion Valve Warm Ambient Air Out
Warm Air In Providing Solutions. Simplifying Regulation.
Vapor Compression Cycle Compressor Cool Ambient Air In Cold Air Out
Heat Exchanger 2 Heat Exchanger 1
Expansion Valve Warm Ambient Air Out
Warm Air In Providing Solutions. Simplifying Regulation.
Refrigeration
• Manipulation of the of the pressure of Substance 1 in order to reduce the temperature of Substance 1 for the purpose of achieving a desired lower temperature in Substance 2. • Substance 1 = Refrigerant • Substance 2 = Air, water, grapes, wine, apples, beef, wine, oranges, peaches, chicken, ice….. Providing Solutions. Simplifying Regulation.
Definitions
• Refrigeration – The process of cooling or maintaining temperature in a space or object by removing heat • Pressure – A force per unit area applied directly to a surface • Temperature – The measurement of the intensity of heat (energy) in an object • Sensible Heat – Heat energy that causes a change in temperature • Latent Heat – Heat energy that causes a change in state Providing Solutions. Simplifying Regulation.
Heat Transfer Equation - Sensible = × × • Where: o Q = heat required (BTU) o M = mass of substance𝑄𝑄 (lb) 𝑀𝑀 𝐶𝐶 ∆𝑇𝑇 o C = specific heat capacity (BTU/lb-ºF) o ∆T = T2-T1 = Difference between the starting temperature and the ending temperature (ºF) Providing Solutions. Simplifying Regulation.
Example 1 • Determine the BTUs required to warm 2 lb of water from 40ºF to 70ºF.
= × ×
= ×𝑄𝑄1 𝑀𝑀 ×𝐶𝐶 ( ∆𝑇𝑇 ) 𝐵𝐵=𝐵𝐵𝐵𝐵 𝑄𝑄 2𝑙𝑙𝑙𝑙 70º𝐹𝐹 − 40º𝐹𝐹 𝑙𝑙𝑙𝑙 � º𝐹𝐹 𝑸𝑸 𝟔𝟔𝟔𝟔 𝑩𝑩𝑩𝑩𝑩𝑩 Providing Solutions. Simplifying Regulation.
Example 2 • Determine the BTUs required to warm 2 lb of iron from 40ºF to 70ºF.
= × ×
= × 0.𝑄𝑄118 𝑀𝑀 𝐶𝐶 × (∆𝑇𝑇 ) = 𝐵𝐵.𝐵𝐵𝐵𝐵 𝑄𝑄 2𝑙𝑙𝑙𝑙 70º𝐹𝐹 − 40º𝐹𝐹 𝑙𝑙𝑙𝑙 � º𝐹𝐹 𝑸𝑸 𝟕𝟕 𝟎𝟎𝟎𝟎 𝑩𝑩𝑩𝑩𝑩𝑩 Providing Solutions. Simplifying Regulation.
Heat Transfer Equation - Latent = × • Where: o Q = heat required (BTU) 𝐿𝐿 o M = mass of substance𝑄𝑄 (lb) 𝑀𝑀 ℎ o hL = specific enthalpy (BTU/lb) Providing Solutions. Simplifying Regulation.
Example 3 • Determine the BTUs required to boil 2 lb of 212ºF water into steam.
= ×
=𝑄𝑄 ×𝑀𝑀970ℎ𝐿𝐿 = , 𝐵𝐵𝐵𝐵𝐵𝐵 𝑄𝑄 2𝑙𝑙𝑙𝑙 𝑙𝑙𝑙𝑙 𝑸𝑸 𝟏𝟏 𝟗𝟗𝟗𝟗𝟗𝟗 𝑩𝑩𝑩𝑩𝑩𝑩 Providing Solutions. Simplifying Regulation.
Heat Transfer Equation - Combined = +
• Where: 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 o QTotal = 𝑄𝑄total heat required𝑄𝑄 (BTU) 𝑄𝑄 o QSensible = sensible heat (BTU) o QLatent = latent heat (BTU) Providing Solutions. Simplifying Regulation.
Example 4 • Determine the BTUs required to boil 2 lb of 40ºF water into steam.
= + = × × 𝑄𝑄𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝑄𝑄𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆= 𝑆𝑆𝑆𝑆 × 𝑄𝑄𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 𝑄𝑄=𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆( 𝑆𝑆×𝑆𝑆 ×𝑀𝑀 )𝐶𝐶+ (∆𝑇𝑇× ) 𝑄𝑄𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 𝑀𝑀 ℎ𝐿𝐿 = ×𝑄𝑄𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇1 𝑀𝑀× 𝐶𝐶 ∆𝑇𝑇 𝑀𝑀 +ℎ𝐿𝐿( × 970 ) 𝐵𝐵𝐵𝐵𝐵𝐵 𝐵𝐵𝐵𝐵𝐵𝐵 𝑄𝑄𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 2𝑙𝑙𝑙𝑙 212º𝐹𝐹= , − 40º𝐹𝐹 2𝑙𝑙𝑙𝑙 𝑙𝑙𝑙𝑙 � º𝐹𝐹 𝑙𝑙𝑙𝑙 𝑸𝑸𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 𝟐𝟐 𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐𝟐 Providing Solutions. Simplifying Regulation.
Heat Energy Profile for Water 300
Solid and Liquid (144 BTU/lb) 250 Liquid and Vapor (970 BTU/lb) 200
150
Temperature (ºF) Temperature 100
50
Solid (2 BTU/lb-ºF) 0 0 200 400 600 800 1000 1200 1400
BTUs Applied From 0ºF Providing Solutions. Simplifying Regulation.
Example 5 • Determine the BTUs required to freeze 2,000 lb (1 ton) of 32ºF water into ice.
= ×
= 2,𝑄𝑄 𝑀𝑀× 144ℎ𝐿𝐿 = , 𝐵𝐵𝐵𝐵𝐵𝐵 𝑄𝑄 000𝑙𝑙𝑙𝑙 𝑙𝑙𝑙𝑙 𝑸𝑸 𝟐𝟐𝟐𝟐𝟐𝟐 𝟎𝟎𝟎𝟎𝟎𝟎 𝑩𝑩𝑩𝑩𝑩𝑩 Providing Solutions. Simplifying Regulation.
Example 6 • If 2,000 lb of ice must be formed in 24 hours, what is rate of heat transfer? = 288, 𝑄𝑄 = 𝑄𝑄̇ 𝑡𝑡 000𝐵𝐵𝐵𝐵𝐵𝐵 𝑄𝑄̇ = 12,000 24ℎ𝑟𝑟 = 𝐵𝐵𝐵𝐵𝐵𝐵 𝑄𝑄̇ ℎ𝑟𝑟 𝑸𝑸̇ 𝟏𝟏 𝑻𝑻𝑻𝑻 Providing Solutions. Simplifying Regulation.
Refrigeration Tonnage • 1 Ton of Refrigeration (Tr) is defined as the amount of heat required to freeze 2,000 lb of 32ºF water into ice. • 1 Tr = 12,000 BTU/hr Providing Solutions. Simplifying Regulation.
Phase Changes
• Boiling Point – At a given pressure, the temperature at which a substance changes from a liquid to a vapor • Saturation – When a substance is at its boiling temperature and is a liquid, vapor, or mixture between the two, it is saturated • Superheated Vapor – A vapor that has increased in temperature after all of the liquid has boiled away without a change in pressure • Subcooled Liquid – A liquid that exists below its saturation temperature Providing Solutions. Simplifying Regulation.
Heat Energy Profile 300
250 Liquid and Vapor 200 Saturated
150
Temperature (ºF) Temperature 100
50
0 0 200 400 600 800 1000 1200 1400
BTUs Applied From 0ºF Providing Solutions. Simplifying Regulation.
1. Compressor
• Requires energy input from surroundings • Refrigerant enters the compressor as a low pressure saturated vapor • Refrigerant is compressed, and exits under high temperature and high pressure as a superheated vapor Providing Solutions. Simplifying Regulation.
2. Condenser
• Uses circulated water and ambient air to reject heat from the superheated refrigerant • Desuperheats discharge vapor, and condenses to high pressure liquid Providing Solutions. Simplifying Regulation.
3. Expansion Valve
• High Pressure Liquid refrigerant is pushed through the expansion valve, causing the pressure and temperature to drop adiabatically • The expansion valve meters refrigerant flow into the evaporator coil based on current refrigeration load Providing Solutions. Simplifying Regulation.
4. Evaporator Coil
• Low temperature liquid refrigerant enters the evaporator and absorbs heat from the air, lowering the temperature of the product and room Providing Solutions. Simplifying Regulation.
Flooded Configuration Providing Solutions. Simplifying Regulation.
Pump Overfeed (Recirc) Configuration Providing Solutions. Simplifying Regulation.
System Complexity Providing Solutions. Simplifying Regulation.
System Complexity Providing Solutions. Simplifying Regulation.
Compressor Providing Solutions. Simplifying Regulation.
Compressor Providing Solutions. Simplifying Regulation.
Evaporative Condenser Providing Solutions. Simplifying Regulation.
Evaporative Condenser Providing Solutions. Simplifying Regulation.
Evaporative Condenser Providing Solutions. Simplifying Regulation.
High Pressure Receiver Providing Solutions. Simplifying Regulation.
High Pressure Receiver Providing Solutions. Simplifying Regulation.
High Pressure Receiver Providing Solutions. Simplifying Regulation.
King Valve Providing Solutions. Simplifying Regulation.
King Valve Providing Solutions. Simplifying Regulation.
Recirculator Providing Solutions. Simplifying Regulation.
Ammonia Pump Providing Solutions. Simplifying Regulation.
Control Valves Providing Solutions. Simplifying Regulation.
Control Valves Providing Solutions. Simplifying Regulation.
Control Valves Providing Solutions. Simplifying Regulation.
Control Valves Providing Solutions. Simplifying Regulation.
Evaporators Providing Solutions. Simplifying Regulation.
Evaporators Providing Solutions. Simplifying Regulation.
Accumulators or Surge Drums Providing Solutions. Simplifying Regulation.
Accumulators or Surge Drums Providing Solutions. Simplifying Regulation.
Plate and Frame Heat Exchangers Providing Solutions. Simplifying Regulation.
Shell and Tube Heat Exchangers Providing Solutions. Simplifying Regulation.
Shell and Tube Heat Exchangers Providing Solutions. Simplifying Regulation.
Jacketed Tanks (Silos) Providing Solutions. Simplifying Regulation.
Relief Valves Providing Solutions. Simplifying Regulation.
Relief Valves Providing Solutions. Simplifying Regulation.
Relief Valves Providing Solutions. Simplifying Regulation.
Ammonia Diffusion Tank Providing Solutions. Simplifying Regulation.
Ammonia Diffusion Tank Providing Solutions. Simplifying Regulation.
Ammonia Diffusion Tank Providing Solutions. Simplifying Regulation.
Oil Draining Providing Solutions. Simplifying Regulation.
Oil Draining Providing Solutions. Simplifying Regulation.
Oil Draining Providing Solutions. Simplifying Regulation.
Oil Cooling - Thermosyphon Providing Solutions. Simplifying Regulation.
Oil Cooling – Liquid Injection Providing Solutions. Simplifying Regulation.
Oil Cooling – Water Cooled Providing Solutions. Simplifying Regulation.
Machinery Rooms Providing Solutions. Simplifying Regulation.
Machinery Rooms Providing Solutions. Simplifying Regulation.
Machinery Rooms Providing Solutions. Simplifying Regulation.
Emergency Control Box Providing Solutions. Simplifying Regulation.
Emergency Control Box Providing Solutions. Simplifying Regulation.
Emergency Control Box Providing Solutions. Simplifying Regulation.
Emergency Control Box Providing Solutions. Simplifying Regulation.
Emergency Pressure Control System Providing Solutions. Simplifying Regulation.
Emergency Pressure Control System Providing Solutions. Simplifying Regulation.
Ventilation Providing Solutions. Simplifying Regulation.
Ventilation Providing Solutions. Simplifying Regulation.
Ventilation Providing Solutions. Simplifying Regulation.
Ammonia Detection Providing Solutions. Simplifying Regulation.
Ammonia Detection Providing Solutions. Simplifying Regulation.
Emergency Controls Providing Solutions. Simplifying Regulation.
Emergency Controls Providing Solutions. Simplifying Regulation.
EPCS 200 25 Relief PSIG PPM Temp. Vent Emerg. Vent Valve Ambient Air In Cold Air Out 225 PSIG
150 Compressor PPM 250 Condenser PSIG Evaporator
King Valve 40,000 E- PPM Stop
Expansion Reject Heat Out Valve 104 Warm Air In ºF Providing Solutions. Simplifying Regulation.
Pipe Providing Solutions. Simplifying Regulation.
Pipe Providing Solutions. Simplifying Regulation.
Insulation Providing Solutions. Simplifying Regulation.
Insulation Providing Solutions. Simplifying Regulation.
Insulation Providing Solutions. Simplifying Regulation.
Questions? Peter Thomas, P.E. Resource Compliance www.resourcecompliance.com (559) 591-8898 [email protected]