Design of an Automatic Control Algorithm for Energy-Efficient ...
Design of an Automatic Control Algorithm for Energy-Efficient ...
Design of an Automatic Control Algorithm for Energy-Efficient ...
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3 System description 35<br />
<strong>of</strong> per<strong>for</strong>m<strong>an</strong>ce <strong>for</strong> three refriger<strong>an</strong>ts <strong>an</strong>d different ambient temperatures are shown in<br />
Figure 3.11. A typical COP around 2 c<strong>an</strong> be seen.<br />
3.3.2 Heat exch<strong>an</strong>ger icing<br />
One main problem <strong>for</strong> the use <strong>of</strong> a heat pump in cars is the icing <strong>of</strong> the front (ambient<br />
air) heat exch<strong>an</strong>ger. Acting as <strong>an</strong> evaporator when heating the cabin, its temperature has<br />
to be lower th<strong>an</strong> the ambient air in order to extract heat from it. Given a humid autumn<br />
or winter weather this c<strong>an</strong> easily lead to condensation <strong>of</strong> water <strong>an</strong>d - below zero degree<br />
- to the development <strong>of</strong> <strong>an</strong> ice layer. This ice will prevent air flow through the structure<br />
<strong>an</strong>d decrease the heat tr<strong>an</strong>sfer (<strong>an</strong>d with it the COP) dramatically. This is not acceptable<br />
since a car heating system has to be able to provide warm air under all circumst<strong>an</strong>ces to<br />
defog the windscreen - especially when it is cold <strong>an</strong>d humid outside.<br />
Deicing<br />
V1<br />
Compressor<br />
V4<br />
HVAC<br />
EV1<br />
EV3<br />
EV2<br />
EV4<br />
PTC-Heater<br />
Condenser<br />
Evaporator<br />
E-Machine-Chiller<br />
Battery-Chiller<br />
Receiver<br />
V7<br />
IHX<br />
Condenser<br />
Mixed Air<br />
Flap<br />
Figure 3.12: The de-icing mode in the ePer<strong>for</strong>m<strong>an</strong>ce heat pump system. [19]<br />
One solution to this problem taken in the ePer<strong>for</strong>m<strong>an</strong>ce system [21] is to temporar-<br />
V8<br />
V3<br />
V2<br />
V6<br />
V5