Fysikalisk modellering av klimat i entreprenadmaskin
This masters thesis concerns a modeling project performed at Volvo Technology
in Gothenburg, Sweden. The main purpose of the project has been to develop a
physical model of the climate in construction vehicles that later on can be
used in the development of an electronic climate controller. The focus of the
work has been on one type of wheel loader and one type of excavator. The
temperature inside the compartment has been set equal to the notion climate.
With physical theories about air flow and heat transfer in respect, relations
between the components in the climate unit and the compartment has been
calculated. Parameters that has had unknown values has been estimated. The
relations have then been implemented in the modeling tool Simulink.
The validation of the model has been carried out by comparison between
measured data and modeled values by calculation of Root Mean Square and
correlation. Varying the estimated parameters and identifying the change in
the output signal, i.e the temperature of the compartment, have performed a
sensitivity analysis.
The result of the validation has shown that the factor with the greatest
influence on the temperature in the vehicle is the airflow through the climate
unit and the outlets. Minor changes of airflow have resulted in major changes
in temperature. The validation principally shows that the model gives a good
estimation of the temperature in the compartment. The static values of the
model differs from the values of the measured data but is regarded being as
within an acceptable margin of error. The weakness of the model is mainly its
predictions of the dynamics, which does not correlate satisfyingly with the
data.
Sebastian Nilsson
2005
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