FöRFATTARE
Larsson, Daniel; Åkerström, Patrik

DATUM
2000-03-01

INSTITUTION
Maskinteknik / Maskinelement

SAMMANFATTNING
Customers demands for cheaper products with great choice opportunities offer challenges for manufacturers to develop a wide range of products or variations, whilst at the same time maintaining low cost and rational manufacture through standardisation. One way of achieving this is to combine standard modules in different ways to create a large number of models. One example of such a product is the cooling unit for freezers and refrigerators. This is the foundation for this master's thesis, which covers the design of a modularised cooling unit for a refrigerator cabinet. A further advantage of a separate cooling unit is the possibility to test the unit before assembly to reduce the occurrence of faulty units and also possibility to use the same unit in different cabinets.

The solution developed is a separable box, containing the whole cooling unit, which can be placed under the cabinet. This closed system is called the primary system. Instead of the usual evaporator a smaller primary evaporator is used. A compact condenser with the same tube-length as today replaces the current condenser design, which takes up a large part of the back of the refrigerator. Inside the cabinet a secondary closed system is mounted. This is connected to the primary system by an interface plate, joined by a screw-union. Moving the condenser under the refrigerator allows cooling air flow through the unit to be made more efficient through the use of triangular channels, one in each back corner of the cabinet.

The primary evaporator cools the secondary condenser through conduction. The secondary system is a self-circulating unit known as a thermosiphon.

The new system, including the compact condenser and the new air channels decrease energy-consumption by 2% compared to the reference refrigerator. The energy-consumption for the whole system increased by 6% compared to the reference tests. This can be decreased by careful optimisation of the both systems.

Thanks to the new channels the cabinet volume is increased by 23 litre or 5%.

ISSN 1402-1617 / ISRN LTU-EX--00/083--SE / NR 2000:083