# Heat circle -- Calculating the air flow needed across a condenser

• yagel2801
In summary, the conversation discusses the need to calculate the necessary air flow across a condenser to properly direct heat emitted from the condenser to the air. The parameters given are a temperature difference of 10-15 degrees Celsius and a coefficient of performance of approximately 3. The manufacturer's data for the fan airflow is 0.67 meters cubed per second, but it is unclear if this can be used. A link to the manufacturer's data sheet is requested. The conversation also mentions a separate fan with a lower airflow capacity, which may not be suitable for the system being described.
yagel2801
Hi!
I need to calculate what air flow needs to flow across the condenser so that the heat emitted from the condenser is directed to the air.
dT=10÷15 [C]
COP =~3
According to the manufacturer's data the fan airflow is 0.67 [m^3/sec] and i need to check if i can use it.
thanks

Welcome to PF.
Please provide us with a link to the manufacturer's data sheet, for the product you are using.

thank you.
https://www.mouser.co.il/ProductDetail/670-OA825EC-UR-1WBXC

yagel2801 said:
thank you.
https://www.mouser.co.il/ProductDetail/670-OA825EC-UR-1WBXC
That's a fan. It doesn't seem to have anything to do with the system/problem described in the first post (it doesn't have the same airflow). Please provide the data sheet for the system in the firs post (an ac unit?) and fully describe the system, application and problem you are trying to solve. We can't read your mind.

 Ehh, maybe I can. Are you trying to size a condenser fan for an air conditioner with evaporator specs as listed in the OP? If so, then no, you can't use a condenser fan that's 35x lower capacity than the evaporator fan. Condenser fans are generally on the order of twice the airflow of evaporator fans. Exactly how much you need...well, again, look at the product data for the air conditioner (and why doesn't it already have a condenser/fan?).

Last edited:
jim mcnamara

## 1. What is a heat circle and how is it related to air flow across a condenser?

A heat circle is a visual representation of the heat transfer that occurs in a condenser. It shows the flow of heat from the hot refrigerant to the cooler air outside. The size of the heat circle is directly related to the amount of air flow needed across the condenser to transfer the heat efficiently.

## 2. How do you calculate the air flow needed across a condenser?

The air flow needed across a condenser can be calculated by dividing the heat transfer rate (in watts) by the heat transfer coefficient (in watts per square meter per degree Celsius) and the temperature difference between the refrigerant and the air (in degrees Celsius). This will give you the required air flow rate in cubic meters per second.

## 3. What factors affect the air flow needed across a condenser?

The air flow needed across a condenser is affected by several factors, including the heat transfer rate, heat transfer coefficient, temperature difference, and the size and design of the condenser. Other factors such as altitude, humidity, and air density can also play a role in determining the required air flow rate.

## 4. Why is it important to calculate the air flow across a condenser?

Calculating the air flow needed across a condenser is important because it ensures that the condenser is able to efficiently transfer heat and maintain the desired temperature in the refrigerant. If the air flow is too low, the condenser may not be able to remove enough heat, leading to a decrease in system efficiency and potential damage to the equipment. On the other hand, if the air flow is too high, it can result in unnecessary energy consumption and higher operating costs.

## 5. Are there any tools or methods to help with calculating the air flow needed across a condenser?

Yes, there are various tools and methods available to help with calculating the air flow needed across a condenser. These include software programs, equations, and charts that take into account the different factors that affect the air flow. It is important to consult with a professional or refer to manufacturer guidelines to ensure accurate calculations for your specific condenser and system.

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