Igloo™ Insulated Freezer Door

Design

The design of this door takes into account
four key criteria:
1. The door must insulate well at -18 to -25 deg C
2. It must inhibit the build up of ice on the non-freezer side of the door
3. It must maintain a good seal
4. While operating in -18 to -25 deg C it will
function without wear on the curtain or door blade

 

Patented Design

This patented tracking system is an essential part of what makes this door unique. The tracking system allows the door to operate continuously with little or no wear on the curtain blade itself. The system also allows for greater speed from the door while still offering a quiet and smooth action. Envico has recognised the environments that these doors operate in and have built in an element of ‘collision’ factor. If the curtain is accidentally hit by a forkhoist the UHMWPE finger will flex enough to dislodge from the track. The door will continue to work until it can be re-inserted into its correct position.

 

What makes it work

The product used in the Igloo curtain is made from polyester staple fibre that is needled into a woven polypropylene carrier cloth. The carrier cloth gives the product excellent tensile strength and very little stretch in either direction. The product is hence very stable and uniform but flexible. The polyester fibre and polypropylene fabric do not absorb moisture and they do not support insects or bacteria. Polyester and polypropylene garments are used for thermal insulation by people all around the world. These garments are used by athletes and outdoors people to keep them warm in very cold climates. This same property inherent in these garments is what gives this product it’s excellent insulating properties.

 

Design Parameters

Heat transmission and flow is an extremely complex and variable process that depends on many factors. In order to arrive at an answer we have used/assumed the following parameters in the calculations.
• Heat Flow horizontal
• Internal wind speed: Still air
• External wind speed of 3.35 m/s
• Thermal conductivity of “ripstop” PVC: K = 0.170 W /mC
• Thermal conductivity of polyester / polypropylene cloth arrangement: K = 0.055 W /mC
• Thickness of non-ventilated air space: 5.0mm
• Average temperature of air space : 10.0 °C
• Temperature difference across air space: 16.7 °C
• Area of compressed doors strips: 5% of total

Thermal Performance

 

Notes

1. Based on -20 °C Freezer and 5 °C ambient
2. Door Size 3.0m x 3.0m
3. Still air to both sides of the door
4. Strip Curtains include 20% allowance for
air infiltration

 

Conclusion

Average U value = 1.54 W/m2C.
Heat Gain anticipated for 3.0m x 3.0m door = 346 Watt.

 

Igloo™ Combo

The IGLOO™ door is designed to be mounted externally of a freezer. We understand the requirements for our products when they have to function and perform in freezer environments. The need for a long term and reliable solution has lead Envico to develop its COMBO system. This system allows for a conventional panel sliding door to operate with the Envico IGLOO™ door.