Re: [TRNSYS-users] Inlet temperature of FP Collector

[Jeff Thornton <thornton@tess-inc.com>]

<I'm using the large scale storage with 30 temperature levels of stratification. On the attachment you can see the temperature profile inside the TES.  The reason I'm trying to maintain low storage temperature is because the needed temperature to deliver into the residents is only around 60C.>

You're running into a typical solar energy issue.  You can size the array to meet the load in the winter (and have it be oversized for the summer) or you can size it to meet the load in the summer and have it undersized for the winter.  Incident solar radiation varies throughout the year - as does your load most likely.  It's an economic decision as to which route you take on sizing.  As for the tank temperatures - unless you get to a boiling condition or material issue, there's no harm in having a hot tank.  You can use the overheat parameter in the differential controller to shut off collection if the tank gets too hot.

<I'm charging the buffer tank with the heat pump. And for the main storage I'm charging it with the flat plate.

 

Aquastat controller: 

Upper input temperature Th - Outlet load temperature (heat pump) 

Lower input temperature Tl - Temperature to heat source (buffer)

Monitoring temperature Tin - Temperature to load (buffer)

 

are these connections correct?>

 

Not really.  You want to charge a storage tank to a known temperature so the upper input temperature (if you're using a differential controller and not just a simple aquastat) is the setpoint of the tank and the lower input temperature is the temperature of the tank.  This will turn the heat pump on when the tank falls UDB below the setpoint and turn it off wheen it rises to only LDB below the setpoint.

 

Jeff

 

---
Jeff Thornton
President - TESS LLC
22 N. Carroll Street, Madison WI USA 53703
Office: (608) 274-2577  Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton@tess-inc.com

On 10/31/2017 1:42 am, Rm Chemilo via TRNSYS-users wrote:

<Thank you for your explanation. Actually, my main problem is with TES and I thought by controlling the inlet temperature of solar coll can help to maintain the low temperature of fluids inside the TES. So, I already got the right amount of TES energy gain to meet the demand, but the problem is the high temperature inside TES. I need to maintain the low temperature inside TES but also produce high energy gain. Do you have any suggestion what should I do?>

<Maintaining high energy gains while maintaining low temperatures is difficult unless you have great stratification and/or a very large storage.  Why are you trying to maintaain low storage temperatures?>

I'm using the large scale storage with 30 temperature levels of stratification. On the attachment you can see the temperature profile inside the TES. 

 

The reason I'm trying to maintain low storage temperature is because the needed temperature to deliver into the residents is only around 60C.

 

 

<I have another question still regarding SHW. I created another SHW simulation and it consists of solar coll, TES, heat pump, and buffer tank. The water to water heat pump (type 927) component acts as auxiliary heating when the heat from solar coll is not sufficient. After I run the simulation, the heat pump works but the outlet temperature really high. I only need to increase the temperature from 40C to 60C but it goes up to 90C. What control should I apply for this problem?>

 

<Are you charging the buffer with the heat pump or are you charging the main storage?  Typically you'd use an aquastat that watcxhes the tank temperature and turns on/off the heat pump.>

 

I'm charging the buffer tank with the heat pump. And for the main storage I'm charging it with the flat plate.

 

Aquastat controller: 

Upper input temperature Th - Outlet load temperature (heat pump) 

Lower input temperature Tl - Temperature to heat source (buffer)

Monitoring temperature Tin - Temperature to load (buffer)

are these connections correct?

 

 

 

 

 

On Tue, Oct 31, 2017 at 9:01 AM, Jeff Thornton via TRNSYS-users <trnsys-users@lists.onebuilding.org> wrote:

<Thank you for your explanation. Actually, my main problem is with TES and I thought by controlling the inlet temperature of solar coll can help to maintain the low temperature of fluids inside the TES. So, I already got the right amount of TES energy gain to meet the demand, but the problem is the high temperature inside TES. I need to maintain the low temperature inside TES but also produce high energy gain. Do you have any suggestion what should I do?>

Maintaining high energy gains while maintaining low temperatures is difficult unless you have great stratification and/or a very large storage.  Why are you trying to maintaain low storage temperatures?

 

<I have another question still regarding SHW. I created another SHW simulation and it consists of solar coll, TES, heat pump, and buffer tank. The water to water heat pump (type 927) component acts as auxiliary heating when the heat from solar coll is not sufficient. After I run the simulation, the heat pump works but the outlet temperature really high. I only need to increase the temperature from 40C to 60C but it goes up to 90C. What control should I apply for this problem?>

 

Are you charging the buffer with the heat pump or are you charging the main storage?  Typically you'd use an aquastat that watcxhes the tank temperature and turns on/off the heat pump.

 

Jeff

 

 

---
Jeff Thornton
President - TESS LLC
22 N. Carroll Street, Madison WI USA 53703
Office: (608) 274-2577  Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton@tess-inc.com

On 10/26/2017 2:07 am, Rm Chemilo via TRNSYS-users wrote:

Thank you for your explanation. Actually, my main problem is with TES and I thought by controlling the inlet temperature of solar coll can help to maintain the low temperature of fluids inside the TES. So, I already got the right amount of TES energy gain to meet the demand, but the problem is the high temperature inside TES. I need to maintain the low temperature inside TES but also produce high energy gain. Do you have any suggestion what should I do?

 

I have another question still regarding SHW. I created another SHW simulation and it consists of solar coll, TES, heat pump, and buffer tank. The water to water heat pump (type 927) component acts as auxiliary heating when the heat from solar coll is not sufficient. After I run the simulation, the heat pump works but the outlet temperature really high. I only need to increase the temperature from 40C to 60C but it goes up to 90C. What control should I apply for this problem?

 

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