Design of next generation Microwave Oven

Start - Finish:

June 2007

Project Members

Yingying Seow

Keywords:

Sustainable design, Microwave oven, Energy efficient heating

Useful Websites:

Wikipedia Microwaves
How does a microwave function

Aims & Objectives:

- To reduce the energy consumption during the use stage through design improvements.

- To investigate the possible reduction in energy use by modifying the oven geometry.

- To build a working prototype to measure potential energy savings.

Project Abstract

A life-cycle analysis was conducted on a traditional microwave oven to evaluate the environmental burdens associated with it. This identified areas of high environmental burden which where considered for incremental redesign. The microwaves in use energy consumption was highlighted as being highly influential on the environmental impact of the oven. This was therefore considered for a more radical redesign, and experimented with various cavity geometries to investigate the effect on energy efficiency. Both qualitative and quantitative analysis indicated that a more considered approach to select internal cavity geometry resulted in a 10% improvement in operating efficiency.

Development and Experimentation

A Life-cycle Analysis (LCA) was conducted for a traditional microwave oven to consider the environmental burdens associated with its manufacture, use and disposal. By far the most impact phase of the ovens life-cycle related to the energy consumed during the 'use' phase. This directed the research to consider the effects of cavity geometry on the resulting efficiency of the food being cooked. Typical ovens use a basic cubic internal cavity, combined with a rotating plate to ensure emitted waves interact with the food. Redirection of these waves to cover more of the internal cavity, could potential improve the cooking efficiency.

Qualitative analysis was undertake via the use of thermal fax paper placed at various positions within the microwave. This created a thermal map of the hotspots within the oven, that could be compared for both the traditional and modified geometry.

Quantitative analysis was then undertaken via measurement of the time taken to heat a bowl of water, using the traditional and adjusted geometry.

Results

From the initial results it was found that there was a slight difference between the cavity with plates attached and the version of the microwave that didn't. Further experimentation indicates the average change in temperature is 11C and 10C for the modified and unmodified cavity, respectively - a 1C improvement in heating efficiency.

Conclusions

Over 22.9 million microwave ovens owed by the UK in 2007, 232,703,380 KWh of electricity can be potential saved.