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  1. heinasirkka

    Effect of thermal inertia at resistance heaters

    Thanks everybody for the answers. Sorry for my interchangeable use of power and energy, I lack some fundamentals in thermodynamics. Compositepro, thermal inertia is indeed a sort of made up terminology, based on the rate of dissipation of the stored heat, and basically represents a system...
  2. heinasirkka

    Effect of thermal inertia at resistance heaters

    Thank you for your answers!
  3. heinasirkka

    Effect of thermal inertia at resistance heaters

    Thank you for your reply LittleInch! The term "real applied heat" is indeed a term found by myself. I just wondered if there will be some kind of discrepancy between the used electrical power and applied heat power at an electrical heater. I suspected that thermal inertia might cause this. I'm...
  4. heinasirkka

    Effect of thermal inertia at resistance heaters

    Hello everybody, I'm confused about how to deduce the real applied heat at an inline resistance heater. The heater I have has 4 heating elements that is in direct contact with the refrigerant. It has rated power of 40kW (each heating element rod has 10kW). I can apply a partial power. However...
  5. heinasirkka

    Start-up precedure of sliding vane pumps?

    Hey Ted, thanks for the reply. I also tried directly starting with high rpm. It still has cavitation. As extra information, we did two leaks tests, one under vacuum and one under pressure. So there should be nothing going in or out of the cycle.
  6. heinasirkka

    Start-up precedure of sliding vane pumps?

    Dear forum users, We have a sliding vane pump installed as inline in a closed-loop power cycle working with a refrigerant. The pump serves for overcoming the pressure drop (1-2 bar). The problem is, the pump cannot deliver any flow. When we are buying from the company, we gave the refrigerant...
  7. heinasirkka

    Pressure drop along an EEV?

    Thank you all for the answers and the links you've provided. I'm looking to them and will also contact with the manufacturers for more detail.
  8. heinasirkka

    Pressure drop along an EEV?

    Dear forum users, I have a theoretical question. We have a cycle where the condensation pressure (temperature) is too high and for reducing it I'll buy an electric expansion valve. It needs to cause a certain pressure drop. In the datasheets the pressure drop and flow rate are correlated, but...
  9. heinasirkka

    Liquid receiver connection

    Hello, Thanks a lot for your answer adammal44. I called it flawed because I myself had to design and build it without enough expertise and know-how at the beginning, and without any supervision and with a hasty time constraint. And I cannot make the cycle work, so now I see that I missed some...
  10. heinasirkka

    Liquid receiver connection

    Dear forum users, I'm working on a closed refrigerant loop built for university experimental research. It has some unconventional and flawed features. There is a liquid receiver at the pump's (sliding vane pump) liquid suction line (thus, between the condenser and the pump). The receiver is to...
  11. heinasirkka

    Filter dryer before rotary pump?

    Dear all, I wanted to write an update for who might be interested. We have realized that a liquid receiver is necessary at the liquid suction line (i.e. between the condenser and the pump inlet). Apparently the pump did not have enough liquid supply and probably it was rotating inside a halo of...
  12. heinasirkka

    Filter dryer before rotary pump?

    There is no restriction before the evaporator. I'll keep the thread updated. Thanks for your interest!
  13. heinasirkka

    Filter dryer before rotary pump?

    "That's what the accumulator is there for to allow you pump up your system. It might start at 7 bar but as you pump in more liquid then the pressure will increase as the bladder distends and the gas pressure behind it increases. - No?" -Yes, I think that can be possible. Pumping more liquid for...
  14. heinasirkka

    Filter dryer before rotary pump?

    The pressure rating of the system is 35 bar. A relief valve is set at that pressure also. The system is completely filled with liquid, and there is no space left.
  15. heinasirkka

    Filter dryer before rotary pump?

    Sliding vane pumps can be used with liquids. Especially low-viscosity fluids (such as refrigerants, petrol). http://www.michael-smith-engineers.co.uk/mse/uploads/resources/useful-info/Pumping-Principles/Vane-Pump-Principles.pdf Sounds like a good idea, however our accumulator is bladder type...
  16. heinasirkka

    Filter dryer before rotary pump?

    The refigerant is neither flammable nor toxic. The dirt and fibers should be with the another filter (not a filter-dryer) in the loop. Furthermore, there is no water in the system. It is also not a refrigeration system. It is an experimental system to test refrigerants heat transfer properties...
  17. heinasirkka

    Filter dryer before rotary pump?

    Thanks for your answers, I really appreciate it. So does that mean that we only can use at given nominal full speed (1450 rpm in our case)? Because our system is for research reasons and we'd like to be able to change the rpm for operating at various flow rates. 1- The pump is flooded with...
  18. heinasirkka

    Filter dryer before rotary pump?

    Thanks! But could you please explain why?
  19. heinasirkka

    Filter dryer before rotary pump?

    Dear forum users, We have built a system however the sliding vane pump seems to be unable to maintain the flow. It starts making strange sounds (maybe it is cavitation). At very low rotation speeds (10% of nominal rpm) there is some flow but when we increase the pump speed, there is even...
  20. heinasirkka

    Curve for sliding vane pump

    Thanks a lot for your helpful answer. The back pressure and the effect of slip were unclear to me, but now I think I get it more. Moreover, I have pressure measurements before and after the pump. Have a nice day!

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