ClassX Video Lessons Youtube Channel The Engineering Mindset Chiller flow rate measurement and calculation, chilled and condenser water
Welcome to an insightful exploration of how to measure the water flow rate through a chiller, a crucial step in assessing the performance of a chiller system and ensuring it aligns with design specifications. Understanding the flow rate is essential for calculating the cooling capacity of a chiller, a topic we have previously covered.
To begin measuring the flow rate, locate the orifice plate within the system. Typically, these plates are identified by two protruding pipes, although the flange face is not visible when connected. Refer to the engineering schematic drawing for precise identification, and consult the drawing legend for additional clarification.
To measure the flow rate accurately, a manometer is required to handle the system’s pressure difference. While compact digital manometers offer precision and portability, older mercury-based models can also be used. Investing in a digital manometer is advisable for ease of use and accuracy.
The simplified schematic of the chilled and condenser water system includes three chillers and three cooling towers, supplying air handling units (AHUs) on both the east and west sides of a building. The flow path of the chilled water is animated for clarity, and the same procedure applies to measuring condenser water. Not all chillers operate simultaneously, typically only during peak demand.
The system divides into primary and secondary circuits, with the east and west wings branching off from a main header. Return water converges into another header before returning to the chillers. This separation is crucial for efficient operation and has been discussed in detail in another video.
In each pump set, only one of the two pumps operates at a time due to a duty and standby configuration. This setup ensures that one pump acts as a backup, and roles are periodically reversed to ensure even wear.
To measure the flow rate, identify a point in the system, such as the orifice plate on the chilled water flow pipe exiting the chiller. Confirm its identity using the drawing legend. Locate the evaporator for chiller number three and trace the pipework to find the orifice plate, typically positioned after the bypass valve.
Orifice plates may be insulated, making them challenging to locate initially. Look for two thin tubes: a blue one indicating the low-pressure side and a red one for the high-pressure side. Plastic tags may also aid identification.
Begin by opening the manometer and identifying the high-pressure side, marked in red. Ensure the top valves for both high and low-pressure sides are closed, and the lower-middle bypass valve is open. Connect the red high-pressure hose to the orifice plate’s high-pressure tube, ensuring a clean and tight connection to prevent leaks.
Eliminate any air pockets in the hose or tubing to avoid measurement inaccuracies. Connect the blue low-pressure hose to the orifice plate’s low-pressure side.
Zero the measurement gauge by opening the high-pressure valve on the orifice plate and the manometer. Adjust the gauge until the ball is level with the zero mark. Once aligned, open the low-pressure side of the orifice plate, tightening connections if necessary to prevent dribbling. Open the low-pressure valve in the manometer and slowly close the bypass valve, allowing the red ball to rise and stabilize before taking a reading.
Note the pressure difference, in this case, 6.2 kilopascals, and disconnect the equipment by reversing the connection process.
To calculate the flow rate, the KVS value provided by the orifice plate manufacturer is required. This value varies by manufacturer, model, and size. Use the chart to mark the pressure reading on the y-axis, draw a horizontal line to intersect the KVS line, and then a vertical line to determine the flow rate, approximately 55 liters per second in this example.
For a precise calculation, use the formula:
Substitute the known KVS value and pressure difference into the formula to find a flow rate of approximately 54.7 liters per second.
By following these steps, you can accurately measure and calculate the water flow rate through your chiller system.
Thank you for engaging with this educational content. For further inquiries, feel free to reach out through comments or explore additional resources on our website, The Engineering Mindset. Stay connected with us on social media platforms for more insightful content.
Engage with an interactive digital schematic of a chilled and condenser water system. Identify key components such as the orifice plate, pumps, and circuits. Use this tool to visualize the flow paths and understand the system layout. This will reinforce your ability to read and interpret engineering schematics effectively.
Participate in a hands-on workshop where you will compare different types of manometers. Evaluate their features, accuracy, and ease of use. This activity will help you make informed decisions when selecting the right manometer for specific chiller systems.
Work through a series of flow rate calculation problems using real-world data. Apply the formula provided in the article to calculate flow rates for different scenarios. This exercise will enhance your mathematical skills and understanding of flow rate calculations.
Engage in a role-playing activity where you troubleshoot a simulated chiller system. Identify issues related to flow rate measurement and propose solutions. This activity will develop your problem-solving skills and deepen your understanding of chiller system operations.
Participate in a peer review session where you present your flow rate measurement and calculation findings. Engage in discussions with classmates to compare methodologies and results. This will encourage critical thinking and collaborative learning.
Here’s a sanitized version of the provided YouTube transcript:
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Hello everyone, this is Paul from The Engineering Mindset. In this video, we will look at how to measure the water flow rate through a chiller. This is useful for analyzing the performance of a chiller and ensuring it meets design specifications. In our previous video, we discussed how to calculate the cooling capacity of a chiller, which requires knowing the flow rate of water through the chiller. You can find a link to that video on the screen or in the description below.
To measure the flow rate, we need to locate an orifice plate in the system. These typically have two pipes sticking out of them, although the flange face won’t be visible when connected to the pipe. You can identify them on the engineering schematic drawing, which should resemble this. Be sure to check the drawing legend for clarification.
Next, we need a tool to measure the flow rate. For this, we require a special manometer that can handle the pressure difference of the system. Compact digital versions are available and are easier to transport and more precise. However, I will be using an older mercury-based manometer simply because that’s what I had available at the time. If you decide to purchase a manometer, I recommend investing a little extra for the digital version; I will leave some links below for your convenience.
This is a simplified version of the actual chilled and condenser water schematic for the building. As you can see, it has three chillers and three cooling towers, which feed the air handling units (AHUs) on both the east and west sides of the building. For this example, I have only animated the flow path of the chilled water, as that is what we are measuring. The procedure will be the same if you want to measure the condenser water. Note that not all chillers need to run simultaneously; this typically occurs only at maximum demand.
On the left, the east and west wings split off from a main header, and the return water joins another header before returning to the chillers. This separates the primary and secondary circuits, which we have covered in another video. You can find that link on the screen if you need to learn more.
Also, notice that only one of the two pumps is running in each pump set. This is due to a duty and standby configuration, where one pump is the leader and runs while the other acts as a backup in case the leader pump fails. These roles are reversed periodically to ensure even wear.
Now, let’s look at a real-world example. First, we need to find a point in the system where we want to measure the flow rate. We will use this orifice plate on the chilled water flow pipe coming out of the chiller. We can check the drawing legend to confirm that this is indeed an orifice plate, which means we can measure here. We need to locate the evaporator for chiller number three and follow the pipework until we find the orifice plate, which is just after the bypass valve.
These orifice plates may be covered with insulation, making them a bit difficult to find initially. However, you can identify them by spotting the two thin tubes that stick out. One tube will be blue, indicating the low-pressure side, and the other will be red, indicating the high-pressure side. They may also have plastic tags to help identify them.
Next, open the manometer and find the high-pressure side, which is colored red. Ensure that the two top valves for the high and low-pressure sides are fully closed, and that the lower-middle bypass valve is fully open. Connect the red high-pressure hose to the high-pressure tube of the orifice plate. You may need to change the connection fitting depending on the valve used. Make sure the threads are clean, as they can often be covered with dust and dirt. Turn it hand-tight and ensure there are no leaks.
Now, check for any air pockets within the hose or manometer tubing and flush these out before continuing, as air pockets can cause inaccuracies in your measurements. Next, locate the blue low-pressure hose and connect it to the blue low-pressure side of the orifice plate.
You will need to zero the measurement gauge. Open the valve on the high-pressure side of the orifice plate, as well as the high-pressure valve in the manometer. Check that the bottom of the little ball within the manometer is level with the zero mark on the gauge. If it’s not level, adjust the measurement gauge accordingly.
Once you are satisfied with the zero alignment, open the low-pressure side of the orifice plate. Sometimes, when opening these valves, they may dribble a little. If this happens, tighten the connection slightly to stop the dribbling. After that, open the low-pressure valve within the manometer. Once that’s fully open, you can begin to close the bypass valve. Close the bypass valve slowly and watch the little red ball rise. If it rises too quickly, open the bypass valve fully to prevent mercury from escaping. Allow it to settle, and once it is stable, you can take a measurement.
Note that the little ball may move slightly due to the pumps and turbulent flow within the pipework. Once you are confident it has settled, take the reading. In this case, it reads around 6.2 kilopascals, which is the pressure difference between the high and low sides of the orifice plate. Make a note of this reading, and then you can disconnect the equipment.
To do this, open the bypass valve and close the high and low-pressure valves within the manometer. Then, close the high-pressure valve on the orifice meter and disconnect the hose. Repeat the same process for the low-pressure side of the orifice.
Now we can calculate the flow rate. First, we need to know the KVS value, which is set by the manufacturer of the orifice plate. The KVS value will vary between manufacturers, model numbers, and sizes of the orifice plate. Ensure you use the correct value, as they usually provide a chart for reference.
Let’s mark our reading on the chart, which was 6.2 kilopascals, on the y-axis. Draw a horizontal line across until it intersects the KVS line. From there, draw a vertical line down to determine the flow rate. In this case, it shows a flow rate of around 55 liters per second.
For a more precise calculation, we can use the formula:
Flow rate (Q) = KVS value × √(Pressure difference) / 36.
We know our KVS value and the pressure difference, so we can substitute those values into the formula. After performing the calculation, we find the flow rate to be approximately 54.7 liters per second.
And there you have it—the water flow rate through your chiller.
Thank you for watching this video. I hope you found it helpful. If you did, please hit the like, subscribe, and share buttons. If you have any questions, feel free to leave them in the comment section below. Don’t forget to check out our website, The Engineering Mindset, and follow us on Facebook, Twitter, and Instagram. Thanks again for watching!
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This version removes any informal language, filler phrases, and ensures clarity while retaining the essential information.
Flow Rate – The volume of fluid that passes through a given surface per unit time. – The engineer calculated the flow rate to ensure the cooling system operated efficiently.
Orifice Plate – A device used for measuring the flow rate of fluids by introducing a restriction in the flow path. – The orifice plate was installed in the pipeline to measure the flow rate accurately.
Manometer – An instrument used to measure the pressure of gases or liquids. – The technician used a manometer to check the pressure difference across the filter.
Pressure – The force exerted per unit area on the surface of an object. – Understanding the pressure changes in the system is crucial for maintaining safety standards.
Circuit – A closed loop through which an electric current flows or may flow. – The electrical engineer designed a circuit that minimized energy loss.
Chiller – A machine that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. – The new chiller was installed to improve the building’s air conditioning efficiency.
Measurement – The process of obtaining the magnitude of a quantity relative to an agreed standard. – Accurate measurement of the components is essential for the assembly of the device.
Capacity – The maximum amount that something can contain or produce. – The plant’s production capacity was increased by upgrading the machinery.
Calculation – The process of using mathematics to find an answer. – The calculation of stress on the beam was necessary to ensure structural integrity.
System – A set of interacting or interdependent components forming an integrated whole. – The control system was updated to enhance the performance of the manufacturing process.
