5 replies to this topic

[go-fish]

How can a site performance test of an air cooled heat exchanger in a closed cooling water system be done if it is designed for summer and test run is done in winter and that too under reduced thermal duty?

 

I looked at ASME PTC 30 Section 3.14 which has a permissible limit for the test parameters which stipulate the maximum allowable differences between the test and the design values. But obviously I am exceeding those limits as the equipment is designed for Middle East August conditions and being proposed to be tested in January.

 

Alternatively, I am proposing that if we can show that if there are total 12 fans and we can achieve the reduced thermal duty in winter with less number of fans as validated by an alternate case run in HTRI then we can achieve a successful site performance test run. What do you think?

Edited by go-fish, 09 December 2024 - 10:47 AM.

[Pilesar]

Your proposal seems reasonable to give a checkmark, but will leave holes in the performance testing. How much confidence would you have in the results? It is common to adjust using simulation within a reasonable range. Extrapolating to ultimate capacity from cold weather might be meaningless and could instead be handled by contracted agreement to postpone testing. That would be my preference as the buyer. Assuming the few fan test resulted in failure, what would happen? Would another test be done in summer anyway? That would be acknowledgement that the few fan test was inadequate. What if the few fan test succeeded and the cooler actually could not perform in the summer heat? Would there be recourse? The only good result of the few fan test would be a successful test and the cooler works in summer also. Would the few fan test really prove that? 

  Is there a way to supply warm air to the cooler using a portable steam heater or propane heater? That seems too much trouble when you could just wait a few months for testing.

[go-fish]

Your proposal seems reasonable to give a checkmark, but will leave holes in the performance testing. How much confidence would you have in the results? It is common to adjust using simulation within a reasonable range. Extrapolating to ultimate capacity from cold weather might be meaningless and could instead be handled by contracted agreement to postpone testing. That would be my preference as the buyer. Assuming the few fan test resulted in failure, what would happen? Would another test be done in summer anyway? That would be acknowledgement that the few fan test was inadequate. What if the few fan test succeeded and the cooler actually could not perform in the summer heat? Would there be recourse? The only good result of the few fan test would be a successful test and the cooler works in summer also. Would the few fan test really prove that? 

  Is there a way to supply warm air to the cooler using a portable steam heater or propane heater? That seems too much trouble when you could just wait a few months for testing.

 

I understand the concerns raised by you. But lot of times, thee things are schedule driven and timing not managed by engineers. Engineers can only suggest the solution. The vendor already did a shop run-in test which checked the fan capability in terms of air flow, noise, vibrations, power and it passed that. Client just wants to see that it can also meet the duty on the site, an addiitonal requirement between Client and us (contractor). I know the proposed solution with few fans is not ideal but something more of a mid way solution if the decision makers cannot wait for another 6-8 months.

[breizh]

Hi,

To be frank, being the client, I will wait for summer to perform the test run and will not sign the acceptance tests before and probably retain some payments.

I guess this is what is going to happen. 

Timing mismatch and/or flaw in the contract.

Good luck anyway.

Breizh

[Hamidpalan]

Hi,

In HTRI rating mode you can calculate and simulate cooler performance in different operating mode. We had the same problem for oil cooler 5000 kw. Just change the air temperature and put process fluid inlet temperature and other parameters like test bench. Finally check if over surface is adequate or not.

If your HTRI file predicts well in cooled climate, your client will accept it for hot climate too.

Regards

Edited by Hamidpalan, 25 December 2024 - 07:58 AM.

[Dacs]

You can do performance testing with whatever site condition you currently have and benchmark it against software (like HTRI). But the issue is you cannot replicate the guaranteed case the AFC is designed for.

 

You're bound to the details in your contract for performance testing. If it says per design case, you're screwed.