spiral cooler/continuous cooling

[heathwood]

I hope you guys can help with a decision we need to make with the cooling of a food product.

The product with the consistancy of jam enters the spiral cooler in 185ml plastic pots at 70deg c. Each pot travels in single file and is in the cooler for 20mins, the capacity is around 330 litres. The total batch is around 800 litres.

At present we are cooling the product with four 750mm dia fans. The last run cooled to around 43deg c with an ambient air temp of 29deg. The exhaust temp was 31deg.
Our target is ambient temperature which can be around 40deg c in summer.

We are about to enclose the spiral in a room 6m cubed for refrigeration purposes.

The big question for me is, are we better to introduce ambient air, cool it then exhaust, or refrigerate the room and recirculate the air within.

I realise the first product in would tend to become too cold using the later method but this might be able to be controlled with airflow within the room by turning on fans as required. also would it be viable to use thermal bricks or similar heat storage methods to store heat between batches.

Any ideas and argument will be most appreciated.

Paul

[sterl]

What Temperature is Too Cold?

It appears your batch only represents about 50-minutes run time. How long the conversion from batch to batch? And do you run 24/7 or ?

Considering how much T-Change you are looking for: Its very possible an indirect Swamp Cooler would do it...Whats your Maximum Dew Point temperature?

In terms of investment: unless the operational time proportion is higher than I suspect it is: you might be well served to consider an Ice Builder employed like a chiller. You would then pump near-ice water through a set of coils only as you needed it....All of which would only activate if the ambient were high. Overnight, and between batches, you would simply accumulate some ice....So your refrigeration capacity required is a fraction of your short-term loading.

[Magoo]

Try having product two or even three wide on belt, if belt can accept that and reduce belt speed, you will need lots of ambient air as a once through cooler system. If required ask local refrig co to price a chiller evap system. Air over product is the critical issue, wind chill factor is important to remove heat from whole product.
Even try spraying product with water in spiral cooler, to aid wind chill cooling, plus lots of air.
magoo

[RefrigNoob]

In rotational plastic moulding we used water atomizers(mist sprayers) behind fans, to reduce their air delivery temperature. Cheap, easy to install. Since you're just looking for that last 3 degress, I'd try that first.