# Heat transfer rates through a bedroom window with and without an A/C unit - PowerPoint PPT Presentation

1 / 10

Heat transfer rates through a bedroom window with and without an A/C unit . Sam Sanderson David Theurer December 2006. Description of Problem.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Heat transfer rates through a bedroom window with and without an A/C unit

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

## Heat transfer rates through a bedroom window with and without an A/C unit

Sam Sanderson

David Theurer

December 2006

### Description of Problem

• A bedroom window has been fitted with a window mounted air conditioning unit. The window has been opened and plexiglas cut and fit to cover the remaining opening.

### Report Question

• How much heat is lost through the window?

• Six scenarios are considered.

• A/C unit with blinds and curtains open

• A/C unit with blinds closed and curtains open

• A/C unit with blinds and curtains closed

• No A/C unit with blinds and curtains open

• No A/C unit with blinds closed and curtains open

• No A/C unit with blinds and curtains closed

### Assumptions

• We will only consider the heat modes of convection and conduction from the room to the window and convection and radiation from the outer surfaces to the outside.

• We assume that the convection coefficient for the inside is 5 and for the outside is 15. These are both in the range of natural convection.

• The room temperature is 70 degrees Fahrenheit and the outside temperature is 22 degrees Fahrenheit.

### Methods

• Temperatures were measured using a temperature gun, inside the room, outside, and the at the outer surfaces.

• Appropriate thermal circuits were constructed for each scenario.

• Heat transfer rates were calculated using the temperatures measured and the circuits.

### Results

ScenarioHeat Transfer (W)

1A/C only 125.5

2A/C w/ blinds 125.2

3A/C w/ blinds & curtains 121.1

4No A/C 124.3

5No A/C w/blinds 121.1

6No A/C w/blinds & curtains 117.3

### Discussion of Results

• We expected the first three scenarios to have a much higher heat transfer rate than the last three scenarios.

• Reasons why they were so similar could be:

• The plexiglas allows high rates of heat transfer, but the two windows stacked together allowed much lower rates of heat transfer which lowered the total heat transfer rates

• Radiation from inside the room is neglected

### Discussion of Results

• We expected the highest heat transfer rate to be scenario 1 and the lowest to be scenario 6. This was true but the numbers were closer than expected.

• Each time more insulation was added (closing the blinds and the curtains) the heat transfer rate dropped with the curtains making the largest difference.

### Recommendations

• In order to minimize the heat loss through the bedroom window, the following actions should be taken:

• The A/C unit and plexiglass should be removed

• The window should be closed

• The blinds should be closed

• The curtains should be closed.