Pump after the heat transfer and pumps it to

Pump

The essential basic necessity of using a pump is to push enough warmth exchange liquid through your sun oriented authorities to effectively evacuate the warmth that the sun is saving in them. Too little stream of liquid or excess of stream of liquid causes less productively and decreases efficiency

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The pump is used in an active type domestic solar water heater system for circulating the liquid heat-carrying liquid in the system. It takes the anti-freezing liquid from the heat exchanger after the heat transfer and pumps it to the solar collector for continuing the circulation and collecting heat from the collectors.

 

Energy and Exergy :

                                   In solar water heater as per the First Law of Thermodynamics, it tells us that energy is a conserved quantity; “Energy can neither be created nor destroyed, it can only be from one form to another”. The Second law of thermodynamics states that processes occur in a certain direction only. Energy has quality and quantity. It is essential to evaluate solar water heaters from the of the Second law of thermodynamics point of view because it is the quality of energy that is significant and not the quantity of energy.

 

 

Exergy Analysis:

                             Exergy analysis is completed with the motto of providing some methods to find the possibilities of improvements in the system. In Exergy analysis of solar water heater, the exergy efficiency of collector, heat exchanger and the pump is calculated. Exergy analysis has been extensively used for the optimization of losses in the systems. Exergy is the expression for the loss that is available due to the entropy and its irreversibility. Exergy is also the amount of extreme work that can be extracted from the system by the contacts of the surroundings. The below exergy analysis is done on a location morocco and the temperature and  solar radiation values are taken for the month july around 11 AM at fez location at Morocco. 

 

Exergy Calculation Data:

 

Collector Characteristics:

Parameters

FPC values

?o

0.82

a1

3.31 W m-2 K-2

a2

0.0181 W m-2 K-1

 

 

Steam table data:

P1

Vf1 (specific volume)

H1 (enthalpy)

S1 (entropy)

1 bar

1.0432 m3/Kg

417.36 KJ/Kg

1.3026 KJ/Kg

 

 

P2

Vf2 (specific volume)

H2 (enthalpy)

S2 (entropy)

1.5 bar

1.0528 m3/Kg

KJ/Kg

KJ/Kg

 

 

Propylene glycol data:

Cp = 3694 J/Kg C

Density, ?=1023.61Kg/m3

 

 

 

Pipe dimensions data:

Outer diameter of the pipe, d0 = 9.525mm

Inner diameter of the pipe, di = 7.035mm

Length of the pipe = 15m (std)

Height between pump and collector = 5m (Assume)

Input pressure to the pump = 1 bar (Assume)

 

 

 

Given Data:

Location Fez (Morocco)

Solar radiation = 230 kwh/m2

Output temperature of the collector = 80oC

Input temperature of the collector = 44oC

Tank top temperature      =69.3oC

                                         = 342K

Tank bottom temperature =44oC

                                        = 317K

Ambient temperature      = 27o   

 

 

 

To find the mass flow rate

Height between pump and collector =5m

Input pressure in pump, p = 1 bar

Enthalpy, H1 = 417.36 KJ/Kg

Entropy, S1 = 1.3026 KJ/Kg

Output pressure in pump, p=1.5bar

Entropy, S2 = 1.4336 KJ/Kg

Specific volume at 1 bar, vf1 = 1.0432

Specific volume at 1.5 bar, vf2 = 1.0528

 

The output water temperature

Outer diameter of the pipe, d0 = 9.525mm

Inner diameter of the pipe, di = 7.035mm

Length of the pipe = 15m

M*Cp*?T = M*Cp*?T

                V =length*

                  V =0.5827m3

                Tx = 41.22oC

 

 

Efficiency of the thermal collector:

 ? = ?o-a1 – a2

 

   ?=23.04%

 

The mass flow rate of the collector:

 

Energy Efficiency * Solar radiation = M*Cp*?T

M = 1.434 Kg/s

 

Pump:

P1 = 1 bar (Atmospheric pressure)

P2 = ?gh

 P2 = 1.5 bar

 

To find pump work:

e1= h1-ToS1

e1 = 26.58 KJ

wp=v*p

v=

=1.048Kg/m3

Wp=52w

h2=h1+wp

h2=417.412

e2= h2-ToS2

e2=26.63KJ                          

?ex (pump)=

?ex (pump)=96%

 

Exergy of thermal collector:

 

       ?ex=

             =

?ex (collector)=39.16%

 

Exergy of heat exchanger

?Tm =

         =29.47 oC

Pen(propylene glycol) = M*Cp*?T

                                       =132.91Kw

Pen(propylene glycol) = Pen(water) = Pen

Pex(propylene glycol) = (1-)*Pen

                                        =13.291Kw

Pex(water)=  (1-)

                  = 0.52Kw

?Px= Pex(propylene glycol)- Pex(water)

       = 12.77Kw

?en=100

?ex =

      =3.912

?ex=4%

 

Conclusion:

                     The exergy analysis is calculated in this paper. It is shown that the amount of solar radiation that falls on the solar collector and the rate of flow of the heat exchanging fluid in the closed loop plays a vital role in the exergy and energy efficiency of the domestic solar water heating system.

 

Suggestion:

                    In our paper, we only considered the glazed type flat plate collector for analysis and it would be great if we considered the impacts of other types of a collector like an evacuated tube or a concentrated collector. In addition to the flat plate collector, we did not consider the possibility of doing exergy analysis on unglazed collector and it would have been a great opportunity to analyze the performance of both the collectors at various climates.

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