Continuous cold chain

From Supply Chain Management Encyclopedia

Russian: Непрерывная холодильная цепь

Continuous Freezing Chain

Perishable goods are the products the quality of which deteriorates in normal conditions, i.e their taste, colour, smell or consistence changes. These are mainly agricultural products to be processed into the food products, as well as perishable raw materials for certain industries. These products have a minor share (2-3%) amount the goods transported by railway transport, however the importance of the cargo flow and the necessity of quality preservation are obvious. The transfer of goods flow from the sender’s warehouse to the receiver’s warehouse is characterized by the term “goods delivery” that should not be considered equal to the term “transportation”. In the first case different factors are accounted for in complex, as for example the expected use of the cargo, capacity and consignments, presence and location of de-loading terminals and warehouses, transport and technical connections between them and so on. For the perishable goods not to loose their consumer appeal specific conditions (mainly the temperature mode) should be created and maintained in cargo storage premises of warehouses and transportation modules, specific templates of cargo formation should be used, etc. To secure the fulfillment of the aforementioned conditions correspondent infrastructure and technological processes[1] should be organized in logistic chains of the system. Such a system was named continuous freezing chain (CFC).

Transport and Warehouse Infrastructure

Transport and warehouse infrastructure of CFC consists of three groups of technical assets:

• Isothermal transport modules (railroad, automobile, sea, river, air);
• Warehouse modules with refrigerator storage facilities of different purposes, including industrial, de-loading, distribution, realization refrigerators as well as initial cooling stations for vegetables and fruit. Home used refrigerators have a certain impact on CFC functioning but are not included into it;
• Transport module maintenance devices: refrigerator depots, technical maintenance and equipment units, sanitary processing units for wagons and containers. Without these installations normal functioning of isothermal transport modules is impossible.

Refrigerated Transport

The aggregate of groups one and three of CFC infrastructure is called refrigerated transport, that includes several types:

• Railroad; automobile; sea; river; air; intermodal (inetrmodal transportation)

Transport modules for the transportation of perishable goods: Perishable goods are transported with the use of railroad transport in the following types of transport modules:

• Isothermal wagons (refrigerator wagons, thermos wagons, milk containers, thermos containers, container wagons),
• Box wagons,
• Universal, isothermal and refrigerator containers

It is also possible to use isothermal containers and wagons cooled with the use of liquid nitrogen and thermoelectric batteries.

Technological Processes in a CFC

The main technological processes of a CFC are the following:

• Preparation of goods for delivery
• Storage in warehouses
• Transportation with the use of different transport modules
• Warehouse and de-loading operations
• Preparation of the goods for realization
• Service of infrastructures.

Specific Features of a Continuous Freezing Chain

The delivery of perishable goods in a CFC has the following specific features:

• The necessity to secure the conditions of loading, de-loading and transportation of the goods that are close to storage conditions in average refrigerators;
• The necessity to carry out goods maintenances along the way;
• Higher inequality, seasonal fluctuations and bigger distances of transportation in comparison with other goods;
• One-wayness of transportation of certain types of perishable products and high coefficient of empty mileage of isothermal transport modules (ITM);
• Considerable weight of the boxing of isothermal wagons and considerable small rate of the use of ITM capacity;
• High cost of perishable goods, isothermal transportation and warehouse modules and maintenance devices;
• High cost of maintenance and repair of transportation and warehouse modules;
• Natural loss of perishable products in the course of delivery;
• Limited maximum terms of transportation and storage.

The said specific features characterize CFC as an expensive and multi-functional system.

Conditions of Functioning of a Continuous Freezing Chain

Certain conditions should be met to guarantee the correct functioning of a continuous freezing chain in accordance with the tasks specified for it (security of the process of perishable goods delivery without loss or quality reduction in shortest possible terms).

1. OF all the required regime parameters of storage and transportation conditions for each perishable product (temperature and humidity mode, circulation and ventilation, etc) should be secured along the whole chain. Depending on these parameters and taking into account the type of refrigeration preparation of a product (cooling, freezing) and external air temperature correspondent transport and warehouse modules are used.
2. THe used warehouse and transport modules should correspond to the nature of cargo flow and be economically justified. Refrigerating warehouses and group isothermal rolling equipment should be present in due amount for big consignments, and single isothermal wagons - for medium-sized consignments. For small consignments of perishable goods container technology of door-to-door delivery without intermediary warehouse collection is economically justified. This enables the carries to speed up cargo delivery and ensure the continuous mature of the freezing chain. Competing modes of transport is this case participate in the process of delivery as partners. Economy decentralization has already led to the changes in cargo flows structure and correspondent changes in ITM structure is required. The activities of small and medium-sized carries show the demand for single isothermal wagons the number of which is currently beyond the required amount. The increase in the number of small-portion deliveries of perishable goods almost completely exterminates the demand for group refrigerator rolling equipment that is gradually being re-built into single isothermal wagons. There is also a tendency to use isothermal containers of huge capacity in our county. This is due to the fact that the accumulation of small consignment products for wagon delivery at the place of production and storage of goods in refrigerators requires time that is a problem for cargo owners.
3. A maximum term of a perishable product’s presence in a CFC should be determined. Each product, following the instructions of technologists, has its maximum storage period in strictly regulated conditions. During such a term the products are not deprived of their application properties and can be realized in good state. The products can not stay in a CFC for the period of time that exceeds maximum storage period.