How to estimate heat load for machinery

[Fletchwarre]

Hello all,

[/indent]We are in the process of renovating a 14,000-square-foot space, and have engaged an A/E firm to specify the requirements for this project. Upon reviewing their recommendations, it appears that they are proposing nearly three times the number of dehumidifier units previously required to maintain the space's specifications (15-30°C and a relative humidity greater than 35%). It seems their approach assumes that all electrical power consumed by the mechanical equipment will be entirely converted into heat.

Given that the majority of the work in this space involves the physical relocation of items, I find it difficult to accept this assumption as accurate. However, I am uncertain about the best method to accurately estimate the true heat load.

Unfortunately, we do not have heat output data from the equipment manufacturers, as the equipment is quite old. I would greatly appreciate any suggestions on how to approach this estimation.

Thank you in advance for your assistance.

 

[Snickster]

What do you mean by Dehumidifier. Are these not typical HVAC units? What is manufacturer and model? What ton cooling does each unit have?

 

[MintJulep]

their approach assumes that all electrical power consumed by the mechanical equipment will be entirely converted into heat.

If it doesn't go into the space as heat, where else would it go?

Electric power becomes heat. All of it. That's not to say the nameplate rating of each machine added together. You need to figure out the actual power use over time.

There are several threads here on the topic. This one for example: thread403-416011

The number of "dehumidifiers" is irrelevant. Total heating and cooling capacity is what's important.

 

[3DDave]

In a system that lifts material out of the working space, some of the energy is being moved elsewhere; for example a material handling conveyor belt. But if items are moved or lifted and dropped in the same environment, then it all eventually gets to become heat.

 

[Sal Sham]

Hi Fletchwarre
If you tell me more about the products and environment with details I can help you more. By the way, it is not logical to transfer all the energy to the heat by the devices. What kind of devices are they? Regarding the humidity, don't you use ventilation in this area? If so, you should consider this parameter in your calculations, it is so important.

 

[HVAC-Novice]

Tell more what is going on. Machinery typically only produces sensible cooling load, not latent (humidity).

And your humidity requirement is a minimum requirement. If there is no maximum requirement, you don't need to dehumidify (except for humans).

 

[LittleInch]

"Given that the majority of the work in this space involves the physical relocation of items"

It's all about where the energy is being consumed.

your electric motor will release some energy, but without know what the load is no one can say.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[QualityTime]

If the motor is 75 kw and the actual running load is 68 kw and the motor is 90% efficient ,,,, the reject heat from the motor is 6.8 kw (10% of 68). The rest of the energy is going into driving your equipment.

What is the mechanical equipment actually doing? Is it some sort of conveyor system?

 

[HVAC-Novice]

the energy that goes into the equipment, also turns into heat. for example, if you operate a drill, all the mechanical energy becomes heat and the drill bit has to get cooled. Plus whatever bearing friction and other losses.
so, if that all is in the same space (motor, and the connected tool, All electricity becomes sensible heat.

There may be some evaporative cooling (drill cooling liquid etc.) that could be water, or oil-based.