.TransiEnt.Producer.Heat.SolarThermal.SolarCollector_L1_constProp

Information

1. Purpose of model

A simple solar collector providing useful energy gain as recommended by EN 12975 steady state thermal performance equation [1]. Effective heat capacity was added for transient behavior according to [2].

2. Level of detail, physical effects considered, and physical insight

No physical but parameter based model. Model considers heat loss to ambience but no convection, and pressure losses (linear or quadratic).

No TILMedia models used because they produce warnings at temperatures below 0°C even if no heat flow is generated.

3. Limits of validity

Without effective heat capacity only valid for steady state performance.

Model ignores wind speed.

4. Interfaces

waterIn: water inlet

waterOut: water outlet

T_in: output of temperature at inlet

T_out: output of temperature at outlet

G: output of total irradiance

irradiance_direct_measured_input: input of direct irradiance

irradiance_diffuse_horizontal_input: input of diffuse horizontal irradiance

5. Nomenclature

(no remarks)

6. Governing Equations

Q= area*((G_total*eta_0)-a1*(T_m-T_amb)-a2*(T_m-T_amb)^2)

G_total = iam*direct_irradiance.irradiance+IAM_diffuse*(diffuse_irradiance.irradiance+ground_reflected_irradiance.irradiance)

iam= if biaxial then iam_obj.value_longitudinal*iam_obj.value_transversal
else
iam_obj.value

T_m=0.5*(T_in+T_out)

waterIn.m_flow + waterOut.m_flow = 0

waterOut.p = if noFriction then waterIn.p+gravAcc*fluidIn.d*(z1-z2) else waterIn.p+gravAcc*fluidIn.d*(z1-z2)-(a*waterOut.m_flow+b*waterOut.m_flow^2)

h=c*T+h_0

7. Remarks for Usage

This solar collector can be used for temperatures below 0°C as well.

8. Validation

not validated yet but tested in the check model "TransiEnt.Producer.Heat.SolarThermal.Check.TestCollectorFluidCycle_constProp"

9. References

[1] P. Kovacs, “Quality Assurance in solar thermal heating and cooling technology – keeping track with recent and upcoming developments. A guide to the standard EN 12975,” Brussels, 2012.

[2] T. Osório and M. J. Carvalho, “Testing of solar thermal collectors under transient conditions,” Sol. Energy, vol. 104, pp. 71–81, 2014.

10. Version History

Model created by Tobias Toerber (tobias.toerber@tuhh.de), Jul 2015

Model modified by Sascha Guddusch (sascha.guddusch@tuhh.de), May 2016

Model modified by Anne Senkel (anne.senkel@tuhh.de), Mar 2017

Model modified by Lisa Andresen (andresen@tuhh.de), Apr. 2017

Model modified by Oliver Schülting (oliver.schuelting@tuhh.de), May 2018: added possibility to use inputs for solar irradiation

Model modified by Oliver Schülting (oliver.schuelting@tuhh.de), Aug 2018: added boolean 'UseStationaryCalculationMethod' to deactive instationary part of heat flow calculation '-c_eff*der_T'. Results are nearly the same but unrealistic peaks can be avoided if calculation is stationary

Model modified by Carsten Bode (c.bode@tuhh.de), Nov 2018: replaced fluid objects by equations, eliminated m_flowInv and x

Model modified by Anne Hagemeier (anne.hagemeier@umsicht.fraunhofer.de), Aug 2021: enabled the model to be useable without fluid ports

Name	Description
Skymodel	choose between HDKR and isotropic sky model
CostRecordSolarThermal	\|Statistics\|Cost specification

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