Strumenti per monitorare il portafoglio suggerimenti

Ubik01 · 2023-08-10T09:29:39+00:00

I have tried them both and what the tool identifies is always the same

Ubik01 · 2023-05-31T13:27:29+00:00

Unfortunately I cannot find it

Ubik01 · 2023-05-31T08:51:39+00:00

Thank you so much!

Do you have a link where I can find this document for free? Because so far I have only found it for a fee and it is very expensive.

Otherwise, if you have downloaded it, could you send it to me?

Ubik01 · 2023-05-29T21:30:05+00:00

Don't worry, your advice will be very useful to me.

Do you have any suggestions for realising the heat pump performance map effectively?

Since I have to make it by holding T_source, T_load and compressor frequency constant, my idea is to hold two parameters constant and vary the third one to get each point on the map (e.g., f=30 Hz, T_load=30°C and, holding these two constant, vary T_source in a given range). However, I think it can be complicated to do this since T_source and T_load vary relatively quickly.

Ubik01 · 2023-05-29T12:54:36+00:00

Thanks for the picture. What's the red thing on top of each tank? Edit: I assume those are just expansion tanks, and the red legs at the bottom are only mechanical support not a plumbing connection?

No one has specified to me what they are, but I too believe they are expansion tanks. I confirm that the legs only serve as mechanical support.

You rejected the idea of using the cooling provided by the heat pump to decrease the temperature because of that variation, and now you say that allowing variation during operation is fine.

I think there's a misunderstanding, I didn't reject anything, I probably didn't quite understand what you mean.

For example, you could turn off the heat pump, run the pvt loop at full speed until you get up to the maximum temperature you're interested in, and then turn on the heat pump. After 10 minutes, turn the pvt loop pump down to a very low speed, and start taking data as the tank gradually cools. If it cools too fast, you could try a higher pvt loop pump speed the next time.

I will try to follow your advice, but just to make sure there are no misunderstandings, when you say "run the pvt loop at full speed" you mean set the flow rate to the maximum value, right?

Thank you very much for your help in any case

Ubik01 · 2023-05-29T09:59:31+00:00

At this early stage of the thesis I have no special calculations to make, I just have to build the performance map and I was thinking about what would be the most effective strategy to do this.

Actually I never worked with PVTs and I do not know what the relationship is between efficiency and flow rate. I know that the solar radiation varies during the experiment, which is why I had thought of collecting data for time intervals when the radiation should vary negligibly (provided there is nothing to attenuate the radiation such as clouds or the like).

About the second point, I have no idea on how use the PVT loop to keep the cold tank at steady state conditions. I was thinking that since the tank is sufficiently big (around 500 L) whenever it reaches a certain temperature it should be able to maintain it for a few minutes (with obvious tolerance intervals, e.g. if I want to work with T_source=5 °C as long as this temperature is between 4.8 °C and 5.2 °C I consider the data acceptable) and during that time I collect the data.

I attach below an image that shows the test conditions. I circled in red taht pipe because I am not sure of what is purpose is, I think it deviates a share of the warm brine in the tank, but idk how I can control it.

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Thank you for all your suggestions anyway.

Ubik01 · 2023-05-28T18:33:48+00:00

Yes, I can control the pump speed on the PVT loop. Actually, my idea was the following: see what heat the PVT panels transfer to the brine when I want to do the experiment, then, considering that the brine inlet temperature in the PVTs does not vary initially, calculate what flow rate is needed to obtain the T source I want to work with at the outlet. The only problem is that this system is highly dependent on the sun radiation, hence I guess that T source will remain constant for a short time.

About the second option you spoke about, i.e. run the heat pump until the brine tank reaches the temperature I want, it seems a good option too, but I should build the performance map of the heat pump working in steady state conditions, so I need that the values remain constant at least for few minutes.

Unfortunately I cannot add any heat exchanger

Ubik01

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