PHE & Cooling Tower Requirement for Genset 3

[simangunsong]

Hi all..

I have no idea how to calculate PHE flow and temperature for Cooling tower. The objective are selecting PHE and cooling tower for genset for my design..
If :
- Genset capacity : 2000 kVA
- Genset heat rejection to coolant : 60816 BTU/min
- Coolant Flow : 436 GPM
- Standard Thermostat (modulating) Range Degree F : 160~185
- Maximum Coolant Temperature at Engine Outlet Degree F : 208
- Genset unit without Radiator.

As Formula : Q = mc(Delta)T
and result, Delta T = 5,123x10^-17 'C

But, as I know, difference temperature from genset and from Cooling tower is not 1.

Thank you for your help.

 

[GroovyGuy]

Hi,
I have never seen a genset engine jacket water cooled via a cooling tower. Wouldn't it be more common to use a radiator?
Is this a prime-power or a standby application?
What is your minimum ambient temperature? ie Will there be a requirement for glycol?
An engine of this size is frequently equipped with an oil cooler and maybe even an intercooler. Is your engine equipped with these, and if so, how do you plan on providing cooling for these additional loops?
Regards,
GG



"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[Artisi]

GG, no reason why a genset can't be water tower cooled.

OP, ask the engine manufacturer, you might be surprised that they might actually know how to do it.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

simangungsong,

I'm not sure what your question is.

I assume PHE stands for Plate Heat Exchanger?? Much better to use full words

Hence you're trying to work out sizes?

The HX will be sized based on max flow and reject heat.

The cooling towers apparently work best with inlet water between 10 to 15F above the ambient air temperature.

So you need this as your start point along with relative humidity levels.



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

 

[DrRTU]

Most gen set manufactures offer remote radiator option. Contact the OEM. They should offer an option which may include additional circulation pump, expansion tank sizing, and fan interlock/staging. Don’t re-invent the wheel and pickup design liability. Most designs we have done included an inline booster pump such as a B&G series 80. An open tower connected to a plate& frame would add complexity and low loads at low ambient issues. Most fluid coolers from the oem utilize large prop fans (60”) w/o drives with the cooler in the horizontal blow thru position. Horizontal expansion tank a few above the cooler.

 

[MintJulep]

Yes, you could use a heat exchanger and cooling tower, but why would you want to?

As noted by DrRTU, remote radiator either from the manufacturer or other supplier will be a cheaper to install and own option.

http://www.onsitepoweradvisor.com/2015/07/22/specifying-remote-radiator/

 

[simangunsong]

Thank you all, for reply my thread..

@GroovyGuy
The radiator function have been change with Cooling tower/Water Cooler.. I'll check and inform you about the ambient temp.. I am newbie about generator/genset, but my job scope is HVAC => PHE (Plate Heat Exhanger) and Cooling tower..I got information from my friend, Generator/Genset specialist do this job, but I interesting to learn..

@Artisi
Yes, you right sir..The generator/genset specialist will do it, but it can solve my mind question. What is the different calculation between Chiller-Cooling tower than Generator-Water Cooler. As I know, the basic formula is same Q=mc(Delta)T.

@LittleInch
Hahaha..Okay sir, next I will use a complete senteces..
As far as I know, The cooling tower selection and Plate Heat Exhanger are Flow rate and Heat Rejection. But, do not forget about the temperature. Because, The temperature to cool a HVAC unit is different with Generator/genset.

@DrRTU
Yes sir,I will contact them. Btw, how complex is the calculation.? Can you give me 1 or 2 example calculation or references. I am so interesting to know..

 

[LittleInch]

Currently your design makes no sense.

It sounds like you're looking at installing a HX between your engine cooling water and some other cooling system (clearly at a lower temperature) and then cooling this other water in a cooling tower??

Why not just use a radiator instead of this complex space consuming power hungry set up?

hence my point that the most efficient temperatures for the secondary cooling system if you still want to do this are related to max air temperature and Relative humidity plus not many degrees C. Hence you can then work out how much secondary water flow you need through your HX to remove all the engine reject heat

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

 

[SAK9]

There is nothing wrong with using a cooling tower to cool a generator engine and is used when the generator is in a basement/difficult location where it is difficult to run a ventilation duct. The down side is a complete system that needs to be maintained and it has got few more components that can fail. Follow these steps:

1. Fix cooling tower temperature range .Tower outlet is usually 6~8 C above your local design wet bulb(highest wet bulb temperature in a year).Tower inlet is tower outlet temperature +6~8C.Discuss with a local cooling tower vendor and they will be able to assist you with this.

2. Obtain quantum of engine heat to be removed from generator vendor

3. Use data 1& 2 to arrive at secondary side water flow rate for the PHE and the cooling tower

4. Size the cooling tower based on data from 1&2

5. Obtain primary side(engine jacket) water flow rate and temperature range from generator vendor


6. Use data from 5 to fix primary side water flow rate and temperature range for the PHE

7. Size the PHE based on data from 3 & 6

 

[simangunsong]

Hi all..

I add some information, such as:
1. Coolant capacity without Radiator (liter) = 170
2. Ambient air temperature (Degree) C = 40
3. Maximum Head Static of Coolant (ft) = 32.8
4. Maximum Outlet Pressure of Engine Water Pump (psi) = 28.6
5. Heat Rejection to Atmosphere from Engine (kW) = 127
6. The selection Generator is Prime Stand-By Power

@LittleInch
The owner ask me if they can joint with the existing. Maybe add a little additional equipments..

@Sak9
I will tried followed your steps and inform again about the result. Thank you.

 

[GroovyGuy]

Hi,
Per your reply above; "6. The selection Generator is Prime Stand-By Power"
Please note that a d-gen unit will have "Prime" & "Standby" power ratings, but my question was pertaining to the actual application. (ie is your application for "Prime" or "Standby" power? It cannot be both!).
If your application is for standby power then I would like to suggest that you install a conventional radiator, and forget the cooling tower approach. A cooling tower is too costly and too complicated for a standby application.
Regards,
GG

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[simangunsong]

Hi GroovyGuy..

The selection generator is Prime Power..
That's I saw from the brochure seletion.

 

[Artisi]

Is this a real job, or make believe "that's what I saw from brochure selection". If this is an actual job, you should explain why you require cooling tower in lieu of conventional cooling.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[MintJulep]

The owner ask me if they can joint with the existing. Maybe add a little additional equipments.

OK, cheap owner.

Firstly: Does the existing cooling tower have 127 kW of excess capacity?

Second: Will hacking into the existing cooling tower actually be less expensive than a remote cooler for the generator?
12 second cost analysis:
Pipes and pumps will be the same cost.
Plate Heat Exchanger is more expensive than remote cooler.
Result of analysis: Use remote cooler.

 

[FreddyNurk]

I have seen newer products on the market that run heat exchangers, either in the coolant loop, or the exhaust, for additional heat recovery applications. This might be one reason for running an additional cooling tower, another is as SAK9 mentioned. Granted, the concept itself is not new.

Whether it all adds up in terms of return on investment for the additional equipment is a different question.

EDMS Australia

 

[LittleInch]

Simangunson. Your data keeps changing. At the top you have 1 MW of reject heart which is actually quite low for a2MW unit. N ow you magically have 127KW. What's going on??

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

 

[simangunsong]

Hi All..

@Artisi
Yes, it is.. I've done create simple system and Plate Heat Exhanger data after followed other similiar project. Finally, my boss said, our job scope do not need include the Water Cooling. Only, Plate Heat Exhanger and the pipe dimension and line.

@MintJulep
I don't know the Cooling tower capacity, I will ask the electrical division. Maybe they know something..
"quote : Result of analysis: Use remote cooler.quote"
Thank you for the information sir..

@FreedyNurk
Thank you for your advise..

@LittleInch
Sir, Are they same meaning.?
1. Generator heat rejection to coolant : 60816 BTU/min
2. Heat Rejection to Atmosphere from Engine (kW) = 127

A new knowledge for me about Generator, 2 type cooling sistem for Generator :
1. Use Jacket Heater - Connect with radiator, or Water Cooler
2. Use Air/Water Cooler - Connect with Air/water cooler or Fan.

 

[LittleInch]

No and neither number is believable.

Assuming your"genset" is a diesel engine or sinister then for a power output of 2000kVA, type looking at a total heat loss of circa 3000 kW. Quite a lot will be heat of the exhaust gasses, but 61000 btu/min equals 1.1 MW. The 127KW might be radiant heat, heat from an oil cooler, heat from the electrical generator but sounds like extra heat not included in the engine coolant figure.

Get your data clear and correct.

Perhaps if tipi posted the data sheet or the male and model of your genset we could all see where these numbers come from.

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

 

[simangunsong]

Hi all..

Thank you for respon my thread..
I've solve this problem..

@Littleinch..
Thank you for your help.
Maybe my data for you is unbelievable but I've got the data from the brochure.
I am sorry,I can't posted the data because I've only the hardcopy..

 

[LittleInch]

Would you please respect us and let us know how you solved it. You've had many responses here, it is not good to simply disappear without properly closing out the post.

If you just tell us the manufacturer and model then we can Google it and look at the data ourselves because it is not really making sense and maybe you have misunderstood something.

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