Thanks for the great video. Please make more videos on HVAC system designs with calculation in different buildings. (May be start with something like single zone design with cooling load & fresh air requirement etc)
hi..i have a question in different subject if you can help in evaporative cooling...is it useful to decrease the temp of water spry or water washer ex: if out air 36c,60%rh..on psy with 90% evaporative efficiency.h ll get a 28c db and 90%rh.. so if i enter a 7c cold water to the washer .will i get a cold air temp....with knowing that in 100%humidity the db is about 27c thanks
We can make industries but the citizens, politicians and bureaucrats are utterly corrupted in Bangladesh. So I don't dare to make and to run the business on it. Thanks from Bangladesh.
Hi Paul, superb illustrations and explanations..Just one small doubt Do we have to get RH of 100% for air coming out from the cooling coil in order to achieve the desired cooling effect...
Good lesson. Small correction - the condensate water term should be negative. energy in = energy out h ent air = Q coil + Q condensate + h lvg air Q coil = Delta air h - Q condensate
Hi, thanks for the video! How do you select a coil to be used in order to achieve a desired cooling capacity? In other words I would like to understand how must I design the coil geometry to achieve certain cooling capacity, with the water inlet & outlet temps. known, air entering temp known etc.
Sir you are saying the relative humidity is 100 persent. But human comfort is 50-55 percent. And also please make an video about relative humidity, specific humidity, dewpoint.
Does the relative humidity affect the enthalpy? According to the air properties i find 99 kJ/kg for h1. But paul uses 78 kJ/kg. What is the reason for this?
You sound Aussie. I assume you're a mech engineer working in HVAC. How's the HVAC job market? I'm planning on heading back to uni to study engineering.
Hey Roy, I'm not Aussie, but I have a mixed accent that often confuses people. I'm a dual mechanical and electrical engineer, working in building services consultancy. In my opinion HVAC is a great career path. You will likely be a mobile engineer and move around different sites meeting very interesting people, plus a lot of equipment is on the roof so you get great views over cities. It's also a job which will be less affected by the automation revolution, and it's in growing demand. No matter how the financial markets affect the world, there will always be the need for an engineer in a building.
good day kind question for this group, i just want to know if there is a formula for cooling capacity which fcu is converted from dx to chilled water or how many percent does of cooling load will be lost if converted?, thank you who ever answers,
Pual my question is when three way valve is activated then in this situation how much water enters into the cooling coil ? Or water completely bypass the cooling coil and goes back in to return line.
Perfect and useful. I wish new videos about cooling coil water pressure drop and air pressure drop. but for the latent heat cooling load calculation, you assumed hw = hf ( heat of vaporization vs heat of saturated liquid)..why?
Could you also explain heating coil capacity? As far as ı know , at heating capacity we should not add humidity counts to Q and Other hand When we cool room , sometımes ıt concludes excessive humidity problems, how we get rıd of it technically. Thanks for efforts🙏🏻
Thanks for this very useful information, can you please let me know the water side pressure drop of cooling coil and the refrigerant required in DX coils for 1 TR of cooling
Thanks for the great video.. so helpful In case we have AHU designed and the evaporator coil sized to specific capacity, can we increase the airflow to achieve higher capacity? A chiller designed to specific capacity and connected to AHU to achieve a certain indoor temperature and air change rate, whats could happen if the AHU coil changed to another one smaller with the same high air flow? The face velocity will be higher? The effects on sensible capacity? The effects on latent capacity? Thanks again
Thanks for this helpful video. I have a question about the air pressure drop, how to calculate it? If you can provide me with some sources it will be better
Our Indoor design will be 23*C , RH - below 60 % . in this case the air which coming out from coil air having almost 100% RH !!! Here how will you control this RH Level??
The air off the coil will be 100% rh , on entering the room i.e air off the grill it will mix with the room condition to make 60%rh i.e 13dec will mix with room condition so it will make 23dec c..since the dbt increase simultaneously the rh tends to reduce
Hello The engineering mindset. I would like to study more about HVAC system. And planning to study abroad. Is there any recommendation which is good university or course? Hope you will reply asap Thank you
partha sarathi Das over time engineers find short cuts and this is one of them, in the real world no one asks for a negative 75kW heat exchanger. You're right it is a negative value though.
Hi! Thank you for your great job! You really understand a lot of things about hvac systems and their components! Please don't stop and continue the great job! Just gonna suggest some themes that I find interesting to understand better so you can maybe had to your list, if you find them interesting: - the various psychometrics evolutions of the air passing through the coils and other components (water cooling and heating coil, dx heating and heating coil, just an electrical resistance, humidification and dehumidification, and maybe others) - how a boiler works and main components (domestic ones (traditional and condensation ones) and industrial ones as you show in one of the videos) - how other type of cooling towers works - the tabs systems (thermo active building systems) Thank you once again and sorry for possible bad english Best regards
At lower temperatures vapour gets saturated even at lower partial pressure. So for a vapour it's easy to attain high relative humidity ,since relative humidity is the ratio of partial pressure of vapour and partial pressure of vapour at saturation.
⚠️ *Found this video super useful?* Buy Paul a coffee to say thanks: ☕
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The Engineering Mindset I would like to buy you a coffee....but in my country pay Pal is not available
Thanks for the great video. Please make more videos on HVAC system designs with calculation in different buildings. (May be start with something like single zone design with cooling load & fresh air requirement etc)
hi..i have a question in different subject if you can help
in evaporative cooling...is it useful to decrease the temp of water spry or water washer
ex: if out air 36c,60%rh..on psy with 90% evaporative efficiency.h ll get a 28c db and 90%rh..
so if i enter a 7c cold water to the washer .will i get a cold air temp....with knowing that in 100%humidity the db is about 27c
thanks
Learn *COOLING LOAD CALCULATIONS* here: th-cam.com/video/0gv2tJf7nwo/w-d-xo.html
We can make industries but the citizens, politicians and bureaucrats are utterly corrupted in Bangladesh. So I don't dare to make and to run the business on it. Thanks from Bangladesh.
Hi Paul, superb illustrations and explanations..Just one small doubt Do we have to get RH of 100% for air coming out from the cooling coil in order to achieve the desired cooling effect...
I was also thinking of the same matter. Unless we use to humidify the cool air after evaporator coil, the RH will not rise to 100% RH.
Yes, you want it to "rain" on the coil, wringing all that water out of the air. That way when you warm 55 F 100% RH air up to 75 F it is at 50% RH.
Good lesson. Small correction - the condensate water term should be negative.
energy in = energy out
h ent air = Q coil + Q condensate + h lvg air
Q coil = Delta air h - Q condensate
Hi, I believe that your formula for Q should not include mw*hw, because this latent heat is included in ma*(h2-h1), am I wrong?
Hi, thanks for the video!
How do you select a coil to be used in order to achieve a desired cooling capacity? In other words I would like to understand how must I design the coil geometry to achieve certain cooling capacity, with the water inlet & outlet temps. known, air entering temp known etc.
Coil geometry and design gets very complex. It takes hours of calculations, you should google the formula Q=U*A*DT as a starting point
Sir you are saying the relative humidity is 100 persent. But human comfort is 50-55 percent. And also please make an video about relative humidity, specific humidity, dewpoint.
0.9m3/kg entering? not 0.887m3/kg? confused....
Sir water inlet temp.to.the cooling coil in ahu is same as chiller set point temperature for calculating kw of cooling coil
Do you have video about BF & CF fsctors of cooling coil. That would be interesting video. Thanks!
Please can you tell us what is the next step after calculate the cooling coil capacity , how to select the correct coil for your application
How did you find water out temp 15c
What about coil efficiency? Are we assuming 100% efficient heat transfer? What is a typical cooling coil efficiency?
Does the relative humidity affect the enthalpy?
According to the air properties i find 99 kJ/kg for h1. But paul uses 78 kJ/kg. What is the reason for this?
You sound Aussie. I assume you're a mech engineer working in HVAC. How's the HVAC job market? I'm planning on heading back to uni to study engineering.
Hey Roy, I'm not Aussie, but I have a mixed accent that often confuses people. I'm a dual mechanical and electrical engineer, working in building services consultancy. In my opinion HVAC is a great career path. You will likely be a mobile engineer and move around different sites meeting very interesting people, plus a lot of equipment is on the roof so you get great views over cities. It's also a job which will be less affected by the automation revolution, and it's in growing demand. No matter how the financial markets affect the world, there will always be the need for an engineer in a building.
hello. how to get the cooling water mass flow rate?
good day kind question for this group, i just want to know if there is a formula for cooling capacity which fcu is converted from dx to chilled water or how many percent does of cooling load will be lost if converted?, thank you who ever answers,
Pual my question is when three way valve is activated then in this situation how much water enters into the cooling coil ? Or water completely bypass the cooling coil and goes back in to return line.
depends on the system, you can check the valve manufacturers documents to see the correlation between position and flow rate
Perfect and useful.
I wish new videos about cooling coil water pressure drop and air pressure drop.
but for the latent heat cooling load calculation, you assumed hw = hf ( heat of vaporization vs heat of saturated liquid)..why?
Could you also explain heating coil capacity? As far as ı know , at heating capacity we should not add humidity counts to Q and Other hand When we cool room , sometımes ıt concludes excessive humidity problems, how we get rıd of it technically. Thanks for efforts🙏🏻
Thanks for this very useful information, can you please let me know the water side pressure drop of cooling coil and the refrigerant required in DX coils for 1 TR of cooling
The specific humidity unit in the condensate water mass flow rate calculation is wrong. It should be in kg/kg.
Thanks for the great video.. so helpful
In case we have AHU designed and the evaporator coil sized to specific capacity, can we increase the airflow to achieve higher capacity?
A chiller designed to specific capacity and connected to AHU to achieve a certain indoor temperature and air change rate, whats could happen if the AHU coil changed to another one smaller with the same high air flow?
The face velocity will be higher?
The effects on sensible capacity?
The effects on latent capacity?
Thanks again
A better teacher than the $3200 class my union provides.
How to calculate the Airout Temperature? How did you arive at 15 Deg C. Please provide calcs?
can you give calculations steps for immersed helical coil in a stationary water tank carrying hot air?
Thanks for this helpful video. I have a question about the air pressure drop, how to calculate it? If you can provide me with some sources it will be better
Hii sir....... Waiting for new videos
Our Indoor design will be 23*C , RH - below 60 % .
in this case the air which coming out from coil air having almost 100% RH !!! Here how will you control this RH Level??
It's just an example. You can sub cool it and then reheat but a more efficient way is to use a Desiccant
Dehumidification unit.
The Engineering Mindset Thanks for your advice!
The air off the coil will be 100% rh , on entering the room i.e air off the grill it will mix with the room condition to make 60%rh i.e 13dec will mix with room condition so it will make 23dec c..since the dbt increase simultaneously the rh tends to reduce
The Engineering Mindset for maintaining 50-60 rh any ancillary is not required for comfort application
Can u tell me about coil in ahu..
Meaning of 4/6 row coil..
When we'd day this ahu is 4 row or any row???
Hello The engineering mindset. I would like to study more about HVAC system. And planning to study abroad. Is there any recommendation which is good university or course? Hope you will reply asap Thank you
Depends where you would like to study. Try courses approved by CIBSE and ASHRAE, which cover building services.
i want to calculate my cooling coil capacity for adding condensing unit more.
you teached me, HVAC and English. thank you!
Glad we could help Cong, keep learning!
here you subtract latent heat why? in the equation above it is adding
In the cooling load calculation , Q_dot should be negative i.e. -78.5 KW. Why have you taken it positive?
partha sarathi Das over time engineers find short cuts and this is one of them, in the real world no one asks for a negative 75kW heat exchanger. You're right it is a negative value though.
Dont you need the Dt to be able to ascertain the 4.67kg/s? How would you have this info without knowing the delta to begin with?
you can rearrange or make iterations
esp calculation pls
How can we calculate cooling water mass flow?
Beautiful, excellent
what if you have a building with hundreds of FCU's in, there must be a quicker way then this
You use a design software to do it all for you
Hi! Thank you for your great job! You really understand a lot of things about hvac systems and their components! Please don't stop and continue the great job!
Just gonna suggest some themes that I find interesting to understand better so you can maybe had to your list, if you find them interesting:
- the various psychometrics evolutions of the air passing through the coils and other components (water cooling and heating coil, dx heating and heating coil, just an electrical resistance, humidification and dehumidification, and maybe others)
- how a boiler works and main components (domestic ones (traditional and condensation ones) and industrial ones as you show in one of the videos)
- how other type of cooling towers works
- the tabs systems (thermo active building systems)
Thank you once again and sorry for possible bad english
Best regards
All good points, Tiago. Thanks
ok
How come you have 100% RH when the air has been conditioned through the cooling coil? Keep up the good videos 👍
At lower temperatures vapour gets saturated even at lower partial pressure. So for a vapour it's easy to attain high relative humidity ,since relative humidity is the ratio of partial pressure of vapour and partial pressure of vapour at saturation.
Can you please upload the duct installation videos based on shop drawings
Great stuff. Hope to see more about HVAC calculations in the coming videos. Well done
Never stop