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nick seghers
15-12-2014, 11:50 AM
Hello,

I have a case where i need to provide a solution to an industrial freezer 14x11m (46x36ft)
= 150m or 500ft. The content will be very expensive. the whole cooling circuit is redundant.

the freezer is already built and it has an electrical resistance wire (redundant) 1600w in total is more then enough i guess.

this is the floor composition from top to bottom:


reinforced concrete 150mm
isolation 2x100mm
redundant electrical resistance wires
vapor barier foil
concrete 100mm



what can we do extra as an addition to prevent the freezer from frost heaving if the electrical resistance wire fails? What can we change or modify to make it even more reliable?

Thank you.

McFranklin
17-01-2015, 04:54 AM
Sorry for the late response, here in the central US what is most common is either air pipes or warm glycol loops.
The air pipes are a series of pipes run in either the bottom layer of concrete or below it. You can either allow ambient air to flow through it or use forced hot air if the local conditions require. This is the most popular, all you have under the concrete is pipe, and potentially the most economical to operate.
The glycol loop is a grid of PEX tubing loops in the concrete, you pump a warm water/glycol mix through the floor. Normally there is a heat exchanger that uses discharge gas from the refrigeration system to warm the glycol. This is a more mechanically complex system (pumps,expansion tanks,heat exchangers) and in the winter there may not be enough heat in the compressor discharge to meet all of your needs.

Magoo
18-01-2015, 12:43 AM
When client insists on heater control for frost protection I install 3 individual circuits 2 as back up all tied to reinforcing steel in bottom slab. never had one fail yet.
Alternatively if you situation changes, use a directional thrusting company and pull tubes under the sub structure and use a glycol solution heated from a discharge HX.

Segei
24-01-2015, 03:02 PM
Sorry for the late response, here in the central US what is most common is either air pipes or warm glycol loops.
The air pipes are a series of pipes run in either the bottom layer of concrete or below it. You can either allow ambient air to flow through it or use forced hot air if the local conditions require. This is the most popular, all you have under the concrete is pipe, and potentially the most economical to operate.
The glycol loop is a grid of PEX tubing loops in the concrete, you pump a warm water/glycol mix through the floor. Normally there is a heat exchanger that uses discharge gas from the refrigeration system to warm the glycol. This is a more mechanically complex system (pumps,expansion tanks,heat exchangers) and in the winter there may not be enough heat in the compressor discharge to meet all of your needs.
Actually, for underfloor heating we need very little heat. Not only discharge gas but refrigerant condensation can be used to warm up the glycol. Every refrigeration plant has plenty of heat for his heating. Some cold storages use refrigeration plant for dock heating in winter time. Requirement for dock heating much greater than requirement for under floor heating.