Etiket Arşivleri: refrigeration

Design of Cold Storage ( PRAGATI SINGHAM )

Contents

 Introduction
 Considerations
 Designing aspects
 Problems associated with cold storage
 Refrigeration system
 Heat load calculations
 References

Introduction

 Cold storage facility for perishable products under controlled conditions

 A cold storage unit incorporates a refrigeration system to maintain the desired room environmental conditions

Classification

 Based on storage conditions
 Short term or temporary (7-10 days)
 Long term (6-8 months)
 Frozen storage (years)

Types of cold storage

Specific considerations

 Uniform temperatures
 Length of air blow and impingement on stored products
 Effect of relative humidity
 Effect of air movement
 Controlling ventilation systems, if necessary.
 Product entering temperature
 Expected duration of storage
 Required product outdoor temperature
 Transportation in and storage area

Cold storage design

1. Selection of site
2. Orientation and building form
3. Size
4. Space requirement
5. Design of building
6. Thermal insulation
7. Refrigeration system for cold store
8. Heat Load calculation


Heat Load Calculation

Factors to be considered in determining refrigeration required for a cold-storage plant. Examples are simplified to illustrate steps necessary to calculate heat load of a refrigerated storage area during cooling and normal storage operation.

Refrigeration ( Y.Doç.Dr. K. BÜLENT BELİBAĞLI )

Basics

Refrigeration is the removal of heat from a material or space, so that  it’s temperature is lower than that of it’s surroundings.

When refrigerant absorbs the unwanted heat, this raises the  refrigerant’s temperature (“Saturation Temperature”) so that it  changes from a liquid to a gas — it evaporates. The system then  uses condensation to release the heat and change the refrigerant  back into a liquid. This is called “Latent Heat”.

This cycle is based on the physical principle, that a liquid extracts heat from the surrounding area as it expands (boils) into a gas.

Refrigeration Load ( Y.Doç.Dr. K. BÜLENT BELİBAĞLI )

REFRIGERATION LOAD

The total rate of heat gain of a refrigerated space through all mechanisms is called the refrigeration load, and it consists of

(1) Transmission load, which is heat conducted into the refrigerated space through its walls, floor, and ceiling;

(2) Infiltration load, which is due to surrounding warm air entering the refrigerated space through the cracks and open doors;

(3) Product load, which is the heat removed from the food products as they are cooled to refrigeration temperature;

(4) Internal load which is heat generated by the lights, electric motors, and people in the refrigerated space; and

(5) Refrigeration equipment heat. which is the heat generated by the refrigeration equipment as it performs certain tasks such as reheating and defrosting