Question

Consider a double-pane window consisting of two glass sheets separated by a \(1-\mathrm{cm}\)-wide airspace. Someone suggests inserting a thin vinyl sheet between the two glass sheets to form two \(0.5\)-cm-wide compartments in the window in order to reduce natural convection heat transfer through the window. From a heat transfer point of view, would you be in favor of this idea to reduce heat losses through the window?

Short answer

Answer: Yes, inserting a thin vinyl sheet between the glass sheets can reduce heat losses through the window from a heat transfer point of view, as it can potentially decrease natural convection heat transfer and increase conduction resistance.

Step-by-step solution

Identify the heat transfer mechanisms

In this scenario, the main heat transfer mechanisms include convection and conduction. Since the airspace is within the window and air is not moving freely in and out of the window, natural convection is the heat transfer through the motion of air caused by temperature differences. Conduction is the heat transfer through the glass and the vinyl sheet.

Discuss the impact on natural convection

By inserting a vinyl sheet, the airspace between the glass sheets is divided into two smaller compartments. Since the dimensions of each compartment are reduced, natural convection is expected to be less effective in each of these smaller compartments. The heat transfer caused by natural convection will be reduced due to the decrease in the size of the compartments and the reduction of temperature differences driving the convective flow.

Discuss the impact on conduction heat transfer

Inserting the vinyl sheet will increase the conduction resistance and the complexity of materials present in the window. Glass has a higher thermal conductivity than most plastics, including vinyl. Therefore, adding a vinyl sheet will effectively increase the overall conduction resistance in the window. This increased resistance will help to reduce heat losses through conduction.

Evaluate the idea from a heat transfer perspective

Based on the above discussions, inserting a thin vinyl sheet between the glass sheets can potentially reduce natural convection heat transfer by creating two smaller compartments. The vinyl sheet will also increase the conduction resistance, further reducing heat losses through conduction. Thus, from a heat transfer point of view, implementing this idea would likely result in reduced heat losses through the window.