6 replies to this topic

[srsh]

How to decide ambient temperature? i have a weather data for the location from last 50 year.

[srsh]

do we need to take mean minimum and mean maximum temperature to decide ambient temperature range or need to consider minimum and maximum temperature for the location even though it's just for a couple of times

[snickster]

HVAC engineers use ASHRAE data for design.  This is probably best data to use and I have used for design ambient temperatures for process systems.  Some Oil and Gas and Refining companies also reference ASHRAE.  Here is a link to ASHRAE data:

 

ASHRAE climatic design conditions 2009/2013/2017/2021 (ashrae-meteo.info)

Edited by snickster, 21 May 2023 - 05:29 PM.

[srsh]

But how to decide ambient range? need to consider extream minimum and maximum for equipment design?

[breizh]

Hi,

Consider these standard used by Engineering companies.

Good luck

Breizh 

[snickster]

As an example of client specification, here is Mobil Oil 1990 specification for determining design temperatures:

 

5.2    Temperature

 

Temperature readings obtained from the US Department of Commerce and local weather stations are:

(a)    Annual Average Temperature    A reference temperature that is used in the evaluation of air coolers and in the calculation of optimum insulation thicknesses.

 

b. Coldest Month Average Temperature   An average temperature based on readings taken during what is normally the coldest month of the year, recorded over a 10‑year period.  This average temperature is used as an indicator of winter severity for heating design.

 

c. Lowest One‑Day Mean Temperature    A temperature that may be required for the minimum design metal temperature for equipment that is significantly pressurized at ambient temperatures.

 

(d)     Extreme Low Temperature    A temperature used in consideration of weather protection requirements.

 

(e)     Heating and Cooling Criteria     Locally established design conditions will govern, if available.  If unavailable, the following should be used:

 

(1)     Winter dry bulb 99% temperature    Temperature maintained or exceeded 99 percent of the time.  This temperature is based on hourly readings during the three coldest months of the year and is used in the design of air coolers, heating systems, and piping systems.

 

(2)     Summer dry bulb 2% temperature    Temperature not exceeded more than 60 hours (2 percent of the time) during the four hottest months of the year.  The 2 percent temperature is used in the design of air‑cooled heat exchangers where failure to condense may cause a safety or product loss problem.  To compensate for local heat sources, a temperature increment [for example, +1deg.C (2 deg.F)] should be added to the 2 percent temperature.  The base temperature so derived after compensation for local heat sources is the base temperature to be used for air‑cooler design [EGE 13‑B‑15, Paragraph 4.2(b)].

 

(3)     Summer dry bulb 5% temperature    Temperature not exceeded more than 146 hours (5 percent of the time) during the four hottest months of the year.  The 5 percent dry bulb temperature is used in the design of air‑cooled heat exchangers.  As above, to compensate for local heat sources, a temperature increment [for example, +1deg C (2 deg F)] should be added to the 5 percent temperature.  The base temperature so derived after compensation for local heat sources is the base temperature to be used for air‑cooler design [EGE 13‑B‑15, Paragraph 4.2(b)].

 

(4)     Summer dry bulb maximum temperature  Maximum dry bulb reading recorded, used as a reference temperature in the design of air coolers.

 

(5)     Summer wet bulb 5% temperature   Temperature not exceeded more than 146 hours (5 percent of the time) during the four hottest months of the year.  The 5 percent wet bulb temperature is used in the design of cooling towers.

Edited by snickster, 21 May 2023 - 07:21 PM.

[shvet1]

@srsh

Refer to a local country code.