Automobile performance acceleration

Catalyst Function. Automobile exhaust catalysts are perfect examples of materials that accelerate a chemical reaction but are not consumed. Reactions are completed on the catalyst surface and the products leave. Thus the catalyst performs its function over and over again. The catalyst also permits reactions to occur at considerably lower temperatures. For instance, CO reacts with oxygen above 700°C at a substantial rate. An automobile exhaust catalyst enables the reaction to occur at a temperature of about 250°C and at a much faster rate and in a smaller reactor volume. This is also the case for the combustion of hydrocarbons. 

Driving by personal vehicle is the most popular mode of transportation. And although there is a desire for a fuel-efficient automobile, fuel efficiency is a consideration well behind style, performance, comfort, durability, reliability, status, and safety. The weak demand for a 40 mpg automobile occurs for several reasons It is not a status symbol (not stylistic), accelerates too slowly (smaller engine), cramps the driver and occupants (smaller interior), and often offers inadequate protection (too light) in case of an accident. 

There has been an accelerated interest in polymer electrolyte fuel cells within the last few years, which has led to improvements in both cost and performance. Development has reached the point where motive power applications appear achievable at an acceptable cost for commercial markets. Noticeable accomplishments in the technology, which have been published, have been made at Ballard Power Systems. PEFC operation at ambient pressure has been validated for over 25,000 hours with a six-cell stack without forced air flow, humidification, or active cooling (17). Complete fuel cell systems have been demonstrated for a number of transportation applications including public transit buses and passenger automobiles. Recent development has focused on cost reduction and high volume manufacture for the catalyst, membranes, and bipolar plates. 

Cell design is also an important factor to improve the performance of SOFC stack/module [15-18]. Use of small diameter SOFC may also give opportunity to reduce operating temperature by increasing the volumetric power density [19]. Thus, they are expected to accelerate the progress of SOFC systems which can be applied to portable devices and auxiliary power units for automobile. 

Performance This dimension refers to the product or service s primary characteristics, such as the acceleration, cruising speed, and comfort of an automobile or the sound and picture clarity of a TV set. The understanding of performance required by the customer and the design of the service or product to achieve the required performance level are key factors in quality-based competition. 

The most widely used cabinet test is the neutral salt spray (Fog) test (ASTM B 117), which consists of a fog of 5 % sodium chloride within the chamber at 35 C [46. Controversy exists over the validity of B 117 as a performance test because corrosion mechanisms are not always the same as those observed in automobile service. Also, not all materials can be successfully evaluated in the test. However, the value of the salt spray test as a quality assurance test is well documented [46]. Several modifications to the salt spray test have been developed including acetic acid salt spray (ASTM G 85, Annex 1), copper accelerated acetic acid salt spray (ASTM B 368), acidified synthetic seawater fog (ASTM G 43, Method of Acidified Synthetic Seawater (Fog) Testing), and modified salt spray (ASTM G 85). ASTM G 85 also includes cyclic tests. 

The autocatalyst operates under conditions that are constantly changing. Cold starts may be required several times a day and even on a motorway, automobiles are regularly accelerating and braking. This will influence the air/fuel ratio and engine temperature. These factors all have an effect on catalyst performance. A typical operating cycle is, therefore ... 

Shukla et al., (2003) have described a process to assess the energy and power requirements of a fuel cell-based automobile. They have estimated that the power plant of a modem car must be capable of delivering about 50 kW of sustained power for accessories and hill climbing, with burst-power requirement for a few tens of seconds to about 80 kW during acceleration. For a car with these performance characteristics, this sets the upper power limit required, but in common usage rarely exceeds 15 kW while cruising. 

When we talk about product performance, we are referring to an overall assessment of a product based on an evaluation of a number of measured parameters. For example, for an automobile we may measure acceleration, handling on the road, cornering, roominess of the interior, the sound levels... 

There are times when the correlation between a specific parameter and the product performance is clear. For instance, in an automobile of a specific size and weight, the more horsepower the engine has, the faster the car can accelerate, and the higher its top end speed (Figure 5.2). 

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