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8
Abstract
Kalenoja, Hanna & Lahti, Elina. Reducing the cold start emissions of
passenger cars. LINKKI 2 Research Programme on Energy Conservation
Decisions and Behaviour.
The share of cold start emissions of the road traffic will increase from 20 % to 60 %
during the next decade, due to the implementation of catalytic converters, which
reduce the amount of high temperature emissions significantly. During the cold start
the amount of fuel consumption and carbon monoxide, hydrocarbon and particulate
emissions is at maximum level, because the start presupposes rich fuel ratio.
Furthermore, the catalytic converter is not active, if the temperature of the exhaust
gases is under 270 - 330 EC. Preheating the engine can reduce fuel consumption
under the start period by 0,1 - 0,3 litres and carbon monoxide and hydrocarbon
emissions by 30 - 50 %. In addition, preheating has been shown to reduce the amount
of particulate emissions and mutagenity of the exhaust gases.
In this study the preheating methods, duration times and frequency among car drivers
in Finland have been examined by a mail questionnaire. Also the attitudes towards
preheating and the factors restricting the preheating have been evaluated.
Approximately 90 % of Finnish passenger cars have a block heater, which electrically
warms up the engine block and the coolant. The number of block heaters has
increased strongly during the years 1970 - 1995, but has slightly decreased at the end
of the decade. In addition, 1,3 % of the passenger cars have a fuel-fired heater.
Heaters are less common at the coastal areas of Finland.
Because the block heater is still highly common device, it could in theory be utilized
in most of the start ups during the cold temperature seasons. However, only
approximately half of the winter season cold starts are preheated. Most of the car
drivers consider preheating unnecessary, if the temperature is over - 5 EC, although
preheating would efficiently reduce fuel consumption and emissions always when the
temperature is below +5EC. Lack of knowledge concerning the recommended
preheating temperatures and duration is one of the most significant limiting factors.
In addition, the availability of network outlets limits the use of block heaters. At
home almost 90 % of the cars equipped with block heater can also be plugged into
the network. At work place for only a third of these cars have access to an electric
outlet.
The recommendations concerning the preheating and including the preheater in the
standard accessory set upon purchasing a new passenger car are the most efficient
means to increase the number of preheaters in the vehicle fleet. The implementation
of new technological innovations like heat storages can be accelerated by subsidizing
the purchase and use. The improvement of technical control systems will reduce the
nuisance caused by plugging and timing of the preheaters. Until now the interest for
the technical control device has been modest.