Possible webpage title: How Does Condensing Water Improve Furnace Efficiency?

[felipe douglas]

Homework Statement

To heat your house when it is especially cold outside, your house is equipped with a condensing furnace. Like any combustion furnace, the condensing furnace burns fuel to produce thermal energy and then uses a heat exchanger to convey heat from the burned gases to the air in your house. What makes it a condensing furnace is the last step: before sending the burned gases out into the outdoor air, this furnace allows water vapor in those gases to condense on part of the heat exchanger and flow as liquid down a drain. Why does allowing water to condense improve the heating efficiency of the furnace?

a. As water vapor condenses into liquid water, it produces a partial vacuum that sucks more fuel into the furnace.
b. Gaseous water is hotter than liquid water, so the water going down the drain is cooler than the water vapor going up the chimney.
c. Liquid water occupies less space than gaseous water, so less heat is lost when liquid water is sent down the drain than when gaseous water is sent up the chimney.
d. Water vapor releases energy when it condenses into liquid water and that extra heat is conveyed to the air in the house.

Homework Equations

none

The Attempt at a Solution

D, because as water is condensed, it is easier for it to transfer heat?[/B]

 

[haruspex]

Homework Statement

To heat your house when it is especially cold outside, your house is equipped with a condensing furnace. Like any combustion furnace, the condensing furnace burns fuel to produce thermal energy and then uses a heat exchanger to convey heat from the burned gases to the air in your house. What makes it a condensing furnace is the last step: before sending the burned gases out into the outdoor air, this furnace allows water vapor in those gases to condense on part of the heat exchanger and flow as liquid down a drain. Why does allowing water to condense improve the heating efficiency of the furnace?

a. As water vapor condenses into liquid water, it produces a partial vacuum that sucks more fuel into the furnace.
b. Gaseous water is hotter than liquid water, so the water going down the drain is cooler than the water vapor going up the chimney.
c. Liquid water occupies less space than gaseous water, so less heat is lost when liquid water is sent down the drain than when gaseous water is sent up the chimney.
d. Water vapor releases energy when it condenses into liquid water and that extra heat is conveyed to the air in the house.

Homework Equations

none

The Attempt at a Solution

D, because as water is condensed, it is easier for it to transfer heat?[/B]

That is not what option d says.