Heat PumpTEAM A: CAROLINE NAKANWAGI

SUNGHEE MIN

THERMODYNAMIC 2014 FALL

OverviewWhat is heat pump?

:Thermodynamic principle

How does a heat pump work?

Advantages of heat pump

Energy types used in heat pump

:Geothermal energy

Types of heat pump

THERMODYNAMIC PRINCIPLEUse a volatile evaporating condensing fluid known as the refrigerant

Works by compressing the volatile liquid to make it hotter on the side to be warmed

→the release of pressure to the side where heat isn’t being absorbed

The below diagram shows an example of a heat pump

1) condenser, 2) expansion valve, 3) evaporator, 4) compressor.

How a Heat a Pump WorksThe refrigerant when it’s in the gaseous state, it’s pressurized and then let to flow around the system by a compressor

→This makes the vapor extremely hot and it’s cooled in the heat exchanger also known as the condenser

→The refrigerant that has been condensed then passes through a metering device

→This leads to a reduction in the pressure of the refrigerant

→The low pressure refrigerant enters another heat exchanger

→Here it absorbs heat and boils

→The refrigerant then returns to the compressor and the cycle is repeated

Generally the heat pump continuously cycles

through the processes of

Compression →Condensation

→ Expansion → Evaporation

The heat pump takes heat from the environment

and channels it into a space or system which

requires heating.

COMPRESSION, CONDENSATION,EXPANSION AND EVAPORATIONInside the chambers of the heat pump is allowed to expand in a continuous process

:when the gas travels through the expansion valve,

the gas absorbs heat in the form of stored energy from the air, water or the ground

As the cycle continues, the gas is compressed and it releases the energy in the form of heat

The performance of heat pump is measured by the C.O.P.( Coefficient of Performance)

:the ratio of the heat pumped into the hot reservoir to the work input to the heat pump

Heat Pumps aren’t 100% efficient

1st Therm. Law: energy can be changed from one form to another but can’t be created or destroyed

2nd Therm. Law: work can be converted to heat but the process isn’t 100% efficient

If the heat pump is doing reversible work, then the Carnot cycle is traversed in the opposite direction

The signs of w and q in the individual segments and the signs of w and q in the overall process are changed

Heat is now withdrawn from the cold reservoir that is the surroundings and deposited into the home, which is the hot reservoir

Since this process isn’t spontaneous, work must be done on the system to effect this direction of heat flow

Heat pumps become less effective as the temperature of the cold air decreases.

Therefore, geothermal heat pumps are better

Advantages of Heat Pumps

Advantages of Heat Pumps

•Saving energy and money

•Protecting environment

•No need of any maintenance

Environmental energy can be from

•Ambient Air

•Water

•Brine (Ground heat)

Geothermal Energy

What is Geothermal Energy?

• Geo (Greek for Earth) Thermal (heat)  

• Temperature of Shallow Crust from 55-75 F(Upper 10 ft.)

to 14,400 (Molten Core -4000 meter to center of core)

Brief History of Geothermal Energy

• Paleo0Indians Usage Dates 10,000 years ago

•Use by Romans- Hot Spas; Hot Running Water

•Early 1800s – Yellowstone hot Spring and Hot Spring

Arkansas

•1830 1st Commercial Use; Asa Thompson

Geothermal Potentials

•Seasonal variations measurable until 10-15 depth

• At 10 meters depth the ground is approximately 1K warmer than the yearly

than the yearly average ambient temperature

• In high depth the temperature rises 2.5-4K each 100meter

• For passive cooling depths of 30-100 meters are suitable

bath in Wooden Tub for $1

Types of Heat Pump

Brine Source Heat Pump

Air Source Heat Pump

Water Source Heat Pump

A. Brine Source Heat Pump: ground heat as the heat source Horizontal Collector Vertical Collector

B. Air Source Heat Pump: air as the heat source-air /water heat pump

External Installation Internal Installation

Air Flow in Heat pump

A sectional drawing

C. Water Source Heat Pump:  ground water as the heat source–water/water heat pump