Suggestions to improve humidity in heat treatment shop

[arunmrao]

I am new to this forum and I am not a professional HVAC person,so sorry, if there are some errors in my post or that it is too basic.

I need to have a high level of humidity in the heat treatment shop. Probably form a mist . This is necessary to improve the RH from 45% to 70% and above.

The castings are hardened by forced air cooling. If I could improve the humidity,the quality of castings would improve a lot.

I planned to use a scrapped fuel injector for spraying. But I am unable to build up pressures of 100 bar and above to form a mist.

I would like to know,if there are simpler methods ,or any assistance to improve the delivery of pressure pump.

Thanks in anticipation.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[willard3]

Hire an Engineer to help you.

http://www.eng-tips.com/faqs.cfm?fid=376

 

[arunmrao]

Thanks Willard for directing me to the FAQ. However,this is not a hobby question,nor do I feel that I have transgressed. There is no harm,if a person active in Materials forum posts a work related question here

Looking towards more participative responses.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[MintJulep]

How big is the space?

Is there airflow? If yes, how much?

What is the air temperature?

I doubt that a fuel injection nozzle will be capable of delivering enough water.

 

[arunmrao]

Mint the cooling space is 500sq ft,ambient temperature is 38-40C and RH is 45%. I planned to use multiple nozzles near 4 man coolers, used for fast cooling. Each blower is equipped with 15HP motor and is directly connected to the fan.

In my plant I had a water curtain and sprinklers system to improve the RH. But in my new place ,this is difficult to implement. I must do, with only available resources.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[berkshire]

Arumrao,

It sounds to me that you need regular misting nozzles, not fuel injector nozzles.Misting nozzles can work on 50 psi of water.

I do not know the equipment you have in your new shop, but one alternative to a misting nozzle is a paint spray gun (hook up the water to the paint tube) if you have compressed air available.
Have you looked into evaporative cooling, where a natural fiber mat is placed over the intake of the fan and water dribbled over it?
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[MintJulep]

Arun,

We need you to more precisely define the system and boundaries.

500 square foot room. Ceiling height?

Solid walls? openable windows? Louvers? No walls at all?

Four fans. Do they recirculate air from within the room, or bring in air from outside?

How much air does each fan move? If you don't have a way to measure that, what type of fan is it? How much power are the motors actually using?

What is the outside temperature and humidity?

 

[Compositepro]

Hi, Arumrao. I've never heard of humidity used to help cooling. I believe you mean to to use a water mist to help cool your casting. The evaporation of water results in a lot of cooling. The resulting increase in humidity is a side effect of the evaporation not a cause of the cooling effect. If your spray totally evaporates in the air prior to contacting your casting you will get a small improvement in cooling of the casting due to lower air temperature (perhaps 10-20F) cooler. Water droplets landing on the casting will dramatically increase your cooling rates. You want a fine mist with a small and controlled water flow rate so as not to cool too fast and shock the casting.

There are many inexpensive spray nozzles available that will operate as low as 25 psi. You do not want to use fuel injector nozzles. These misting nozzles spin the water flow as they leave the nozzle so the stream breaks-up into a cone shaped spray.

The cooling rate will be proportional to the water flow rate. Misting nozzles designed for cooling people have very low flow rates because they are designed to only cool the air and not get people wet.

 

[SAK9]

Arun,

If you need humdity in excess of 70%,an airwasher is the way to go.Air washers typically deliver air change rates in excess of 50 which you can not deliver with fans with mist nozzles.Air washers use a water spray curtain or wet pad.

 

[arunmrao]

Sorry for the delay in responding. Thanks all for your helpful comments. I shall try a few and probably share my experience.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year