CmAnD
Mechanical
- Jan 28, 2008
- 15
I am young mechanical engineer and I am a relatively new in this field, but in front of me is a very responsible task.
The company for which I work in the near future is starting with production of air to air recuperative heat exchangers. My task is to give a proposition for layout of equipment for evaluation of the performance of the heat exchangers in order to collect performance data.
I have done a lot of work until now but I have some questions about some of my doubts. So I will appreciate any suggestion about this issue.
Everything is clear for me when the dry effectiveness of heat exchanger is examined. You do one evaluation measurement with inlet conditions prescribed in the standards and you calculate all the necessary values. After that, you make another measurement with different inlet conditions without condensation (different combination of flow rates on exhaust and supply side) and you calculate the effectiveness and other necessary values. With this collected data you make correction factor that can be used for calculation of effectiveness and outlet temperatures for any combination of inlet flow rates on the side of exhaust and supply air.
But, as I can see at this stage of my knowledge, you cannot do the same when condensation occurs.
My question is: Do I need to make measurements for every combination of air flows rates and any combination of humidity values on the exhaust and supply air at different temperatures in order to collect data for whole working range of the heat exchanger?
If I must do it, how the equipment should look? Can I put all dryer, humidifier, heater and cooler in a duct line, or chambers should be build where the air with specified condition will be made and extracted from it and guided to the heat exchanger.
It sounds very hard for me!? Almost impossible!?
I ask myself how can you keep the state of equilibrium enough long to collect necessary data.
Maybe I have to learn some more theory of wet air?
I expect your comments and advices.
Thank you in advance!!!
The company for which I work in the near future is starting with production of air to air recuperative heat exchangers. My task is to give a proposition for layout of equipment for evaluation of the performance of the heat exchangers in order to collect performance data.
I have done a lot of work until now but I have some questions about some of my doubts. So I will appreciate any suggestion about this issue.
Everything is clear for me when the dry effectiveness of heat exchanger is examined. You do one evaluation measurement with inlet conditions prescribed in the standards and you calculate all the necessary values. After that, you make another measurement with different inlet conditions without condensation (different combination of flow rates on exhaust and supply side) and you calculate the effectiveness and other necessary values. With this collected data you make correction factor that can be used for calculation of effectiveness and outlet temperatures for any combination of inlet flow rates on the side of exhaust and supply air.
But, as I can see at this stage of my knowledge, you cannot do the same when condensation occurs.
My question is: Do I need to make measurements for every combination of air flows rates and any combination of humidity values on the exhaust and supply air at different temperatures in order to collect data for whole working range of the heat exchanger?
If I must do it, how the equipment should look? Can I put all dryer, humidifier, heater and cooler in a duct line, or chambers should be build where the air with specified condition will be made and extracted from it and guided to the heat exchanger.
It sounds very hard for me!? Almost impossible!?
I ask myself how can you keep the state of equilibrium enough long to collect necessary data.
Maybe I have to learn some more theory of wet air?
I expect your comments and advices.
Thank you in advance!!!
