truck-trailer refrigeration equipment

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Copyright © 2014 Delmar, Cengage Learning Truck-Trailer Refrigeration Equipment Instructor Name: (Your Name) 13 CHAPTER

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CHAPTER. Truck-Trailer Refrigeration Equipment. 13. Instructor Name: (Your Name ). Learning Objectives. Describe air circulation through the cargo area. List three different forms of short cycling. Explain the operation of the thermostat. Describe the refrigeration unit operation. - PowerPoint PPT Presentation

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Page 1: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Truck-Trailer Refrigeration Equipment

Instructor Name: (Your Name)

13CHAPTER

Page 2: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Learning Objectives

Describe air circulation through the cargo area. List three different forms of short cycling. Explain the operation of the thermostat. Describe the refrigeration unit operation. Explain the reasons for pre-cooling trucks and

trailers. Explain loading procedures to ensure proper

circulation .

Page 3: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Learning Objectives (continued)

Describe cargo floor construction. Explain a pre-trip inspection. Describe the advantages of multi-temperature

refrigeration units.

Page 4: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Trailer Refrigeration Unit

Page 5: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

System Components

Engine- Typically a four cylinder diesel. Compressor- Range from 2 to 4 cylinder. Condenser- Dissipates heat from trailer to ambient

air. Thermostatic Expansion Valve- Fixed orifice,

externally equalized. Evaporator- Absorbs heat in the trailer. Microprocessor- Brain of unit. Controls all aspects

of refrigeration and heating process.

Page 6: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Typical Refrigeration Engine and Microprocessor

Page 7: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

System Components (continued)

Box Temperature- The actual temperature in the storage unit.

Set Point- Optimum temperature to maintain product.

Thermostat- Sets the temperature that the equipment will maintain.

Refrigerant- Chemical used to absorb and dissipate heat in the storage area.

Page 8: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Trailer Refrigeration System Layout

Page 9: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Trailer floor Construction

Fabricated from Aluminum

Forms ductwork under cargo for air circulation

Must be kept free from debris that can impede air flow

Page 10: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Multi Temperature Refrigeration Units May have up to three units. Each unit has its own evaporator and

thermostat. Unit can store fresh, frozen and dry goods

together.

Page 11: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Multi Temperature Trailer

Page 12: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Pre Cooling Products

Product must be cooled to the holding temperature prior to loading trailer.

Trailer refrigeration equipment is designed to maintain temperature of product not cool it down.

Pre cool the trailer prior to loading. Shut down refrigeration unit while loading to

prevent refrigerated air from escaping.

Page 13: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Proper Loading Procedures• Pallets must be loaded so skids allow air flow

fore and aft in trailer.• Product must be kept away from walls to allow

air flow around all sides.• Ample air space must be allowed between load

and ceiling.• Air space must be left between cargo door and

cargo.• Air space must be left between front bulkhead

and cargo.

Page 14: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Proper Pallet Placement

Page 15: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Proper Cargo Loading Technique

Page 16: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Improper Loading of Cargo

Page 17: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Short Cycling Cargo is blocking units discharge air flow. Cold air is routed back to air inlet. Thermostat thinks it has reached set point and

switches to heat mode. Warm air flow is blocked and routed back to air

inlet. Thermostat thinks it has reached set point and

switches to cool mode. Process continues over and over, “Short

Cycling.”

Page 18: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Auto Stop/Start Auto stop/start used by most equipment today. Constant run mode still available. Constant run mode, unit cycles between heat and

cool mode. Auto stop/start mode, unit will shut down once set

point is reached and programmed parameters are met.

Programmed parameters- unit must run long enough to charge battery and warm the engine.

Unit stays off until box temperature reaches preset temperature.

Page 19: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Summary

Microprocessors control all aspects of refrigeration and heating cycles.

Modern advances in technology allow distribution to market fresh fruit and vegetables any time of year.

Loads must be pre cooled to remove residual heat and humidity.

The box must be pre cooled to remove residual heat and humidity.

Page 20: Truck-Trailer Refrigeration Equipment

Copyright © 2014 Delmar, Cengage Learning

Summary (continued)

Correct loading is essential to product quality. Discharge air must be able to circulate freely

around all side of the product. Rising fuel costs have contributed to the

technology for auto stop/start. The auto stop/start feature is a huge financial

savings for the company using it , as well as a way of conserving our natural resources.