MT 1 will be on Wednesday Oct. 31st, 2012 at 1830.

MT 1 will include:Introduction (Chapters 1-2)Cars, planes, freight (Chapter 3,5,A, some of 15 on freight)Wind (Chapters 4, B)Heating and Cooling (Chapters 7, E)

Heating and Cooling

Domestic Water Heating

Heat Capacity: (CV) Amount of heat necessary to change the temperature by 1 ºC per unit volume

For water CV=4100 J / liter / ºC

Energy required to heat water in a bath from 10ºC to 10ºC ?

Domestic Water Heating

The two dominant reasons why buildings lose heat are:

The two dominant reasons why buildings lose heat are:

1. Conduction – heat flowing directly through walls, windows anddoors;

2. Ventilation – hot air trickling out through cracks, gaps, or deliberateventilation ducts.

Conduction Loss:

Related to the conduction of the wall

Ventilation Loss:

The number of changes N of the air per hour, The volume V of the space in cubic meters, The heat capacity C,The temperature difference DT between the inside and outside of the building

78 %

22 %

Total leakiness of the house: 322 W/ºC = 7.7 kWh/d/ºC

The heat-loss parameter of this house (total floor area 88m2) is:3.7 W/ºC/m2

Let’s use these figures to estimate the house’s daily energy consumption on a cold winter’s day, and year-round.

The heat-loss parameter of this house is reduced by about 25%, from 3.7 to 2.7W/ºC/m2.

1.1W/ºC/m2 required of a “sustainable” house in the new building codes

Further reduced the consumption by reducing the thermostat setting from 20 to 17ºC.

Air-exchange

Once a building is really well insulated, the principal loss of heat will be through ventilation (air changes) rather than through conduction.

Hot Air

Cold Air

Air-exchange

Once a building is really well insulated, the principal loss of heat will be through ventilation (air changes) rather than through conduction.

Hot Air

Cold Air

Can we cool down the hot air before it leaves the house?

Nose

Exercise:

Consider a 100 m2 sustainable house in İstanbul with 1.1W/ºC/m2 energy consumption.

Let’s use these figures to estimate the house’s daily energy consumption on a cold winter’s day, and year-round.

1.1x20x100 = 2200 W

2200 W consumed during one day : 2.2 kWx24 h=52.8 kWh/day

For a cold Day: DT=20ºC

http://weather.sg.msn.com/monthly_averages.aspx?wealocations=wc:TUXX0014&q=%C4%B0stanbul%2C+TUR+forecast:averagesm

For an average day: DT= ?

For an average day: DT= 20-14 ºC

1.1x6x100 = 660 W

660 W consumed during one day : 0.66 kWx24 h=15.8 kWh/day

Exercise:

What are the main mechanisms that lead to heat losses in a building?

Exercise:

What are the main mechanisms that lead to heat losses in a building?

ConductionVentilation

Exercise:

Looking at the plot below estimate the energy consumption of a modern 50m2 apartment in Istanbul in February and in November.

Assume energy consumption to be 1.1W/ºC/m2 for the modern apartment.

Exercise:

Rate at which energy is produced by a wind mill is given by the equation below. Interprete this equation and describe the factors effecting the generated power.

Exercise:

Heat loss due to conduction is quantified by the equation below. Interprete this equation and describe the factors effecting the generated power.

Exercise:

Heat loss due to ventilation is quantified by the equation below. Interprete this equation and describe the factors effecting the generated power.

N number of changes of the air per hour

Exercise:

Describe the main principle of energy generation with a windmill. What is the nature of energy in the wind and how is it converted to electricity?

Exercise:

What can be done to reduce the heat losses due to conduction and ventilation in a building?

Exercise:

What are some exemplary geographic locations where wind speed is highest in Turkey? What are the average wind speed values n those regions? How does wind speed change with altitude?

Exercise:

What are the main parts of an AC power generator. Describe its principle of operation.

Exercise:

What is heat capacity? Can you estimate the energy required to boil water in a kettle that is totally filled?

For water CV=4100 J / liter / ºC