Overview
Heat pump black box model with two simple heat exchangers, no
controllers included.
Works as on/off-controlled heat pump or heat pump with capacity
control. The type of capacity and electrical power calculation can be
chosen:
- Polynom
a) depending on evaporator input temperature, condenser output
temperature and variable speed (via conditional speed connector)
for capacity controlled heat pumps
b) depending on evaporator input temperature, condenser output
temperature and nominal speed for on/off-controlled heat pump
- Table data according for on/off-controlled heat pump, depending
on evaporator input temperature, condenser output temperature
Assumptions
Correction models of the calculation can be activated that effect the
efficiency or the start-up and shut-off behavior of the heat pump.
- Icing and Defrosting: Simple model that uses the evaporator inlet
temperature and calculates a factor for CoP correction (according to
Wetter and Afjei, 1996). Not enabled for table data, as usually
already included (data according EN255 and EN14511).
- Mass flow in condenser/evaporator: Model according to Pahud and
Lachal, 2004, that corrects the temperatures used within table and
polynomial. If the mass flow rates are already taken into account in
the chosen polynomial, this sould be deactivated!
- First order behavior of heat pump capacity: Start-up and shut-off
of heat pump can be modeled with a first order behavior.
- Electric efficiency: The electric efficiency of the electric
drive is implemented to calculate the evaporator heat flow
- Scaling factor: A scaling facor is implemented for scaling of the
heat pump power and capacity without effecting the heat pump
efficiency which is not physically correct but may be helpful for
rough calculation.
- Additional electric power: This is a constant value that is added
to the power consumption. This may be helpful if e.g. an electric
drive operates together with the compressor and shall be included in
overall electric power and CoP calculation.
- The smoothness of table interpolation can be chosen.
- Allowed sink temperature: A maximum condenser outlet temperature
limits the condenser heat flow through a PID controller.
Known Limitations
- Allowed source temperature: No limits for source temperature is
implemented. Though, usually this is not a problem if the heat pump
is properly integrated into a system model.
- Defrost: No direct implementation of defrost behavior. This heat
pump does not operate in a defrost mode. Only a general CoP
correction can be chosen therefore.
Concept
The heat pump speed is helt between the boundaries N_min and N_max
even if the input speed is higher or lower. But no further
controlling is implemented. The control logic is conciously not
integrated into this model.
The calculation of the capacity and electric power does not represent
any dynamic behavior of the refrigerant cycle as it occurs in real
heat pumps. Therefor two possibilities exist, to add dynamic
behavior:
- The condenser and evaporator can be parametized with a certain
external fluid volume to represent their thermal inertia in the tab
Evaporator/Condenser
- A first order element can be added to the calculation in the tab
Advanced if the check box PT1_cycle is enabled (see: Correction
models)
References
Sources:
- Pahud, D. and Lachal, B.: Mesure des performances thermiques
d?une pompe à chaleur couplée sur des sondes géothermiques à Lugano
(TI). Office fédéral de l'energie, Bern, Switzerland. 2004.
- Wetter, M. and Afjei, T.: TRNSYS TYPE 401 -
Kompressionswärmepumpe inklusiv Frost- und Taktverluste.
Zentralschweizerisches Technikum Luzern - Ingenieruschule HTL,
Switzerland. 1996.
Example
See AixLib.Obsolete.Year2024.Fluid.HeatPumps.Examples.HeatPumpDetailed
-
June 23, 2015 by Kristian Huchtemann:
formatted for use in AixLib
-
December 10, 2013 by Ole Odendahl:
Formatted documentation appropriately
-
March 27, 2013 by Kristian Huchtemann:
Corrected connection of evaporator inlet and outlet temperature
connectors. Added maximum condenser temperature implementation.
-
January 09, 2006 by Peter Matthes:
V0.1: Initial configuration.
Contents
Name | Description |
---|
Medium_con | Medium outside the refrigerant cycle (Condenser) |
Medium_eva | Medium outside the refrigerant cycle (Evaporator) |
data_poly | Polynomial heat pump characteristics for inverter heat pump |
Corr_icing | Frost/Defrost model (only air-to-water heat pumps) |
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