Question

- Discuss the operating principles of both heat pumps and industrial refrigeration systems.

- Assess the factors that influence the economics of heat pumps. -

- Discuss the apparent contradiction between refrigeration cycles and the second law.

- Conduct a cost-benefit analysis on the installation of a ground source heat pump on a smallholding. Present your findings in the form of academic poster/presentation

Answer 1

HEAT PUMP AND INDUSTRIAL REFRIGERATION SYSTEM

Heat pump and refrigeration system works on same principles although their objectives are different.

Heat pump is used to take heat from environment and deliver it to space needs to be heated.Refrigerator takes away heat from the space to be refrigerated and delivers it to environment.Both need input power for their operation and both are cyclic devices

Their performance is measured with the term known as coefficient of performance or COP

Heat pump's performance is dependent on several factors such as

• Working temperatures of place needs to be cooled or heated as well as environment
• Auxiliary components involved. They must be frictionless to avoid excessive losses. More will be friction more Winput will be needed for running them.
• Components must be leak proof.
• Components should not be big as it will increase initial cost of installation as well as other costs such as replacment and maintanence by several factors.
• Compressor should be of high energy efficiency rating as it consumes a lot of power and primarily responsible for overall power consumption.

According to 2nd law of thermodynamics, heat flows from high temperature to low temperature spontaneously. Second law of thermodynamics tells us direction in which heat transfer will takes place.

If a metal rod is heat at on end, heat will flow from heated end to colder end automatically.In case of refrigerator heat flows from refrigerated space to surrounding which is not possible.

As refrigerated space is cold and environment is hot how can it flow in reverse direction?

"Clausius Statement "

It's impossible to develop a cyclic device which takes heat from lower temperature and delivers it to higher temperature without external Work input .

In other words COP of this device can't be infinity.

So refrigerator without any work input violates Clausius statement or 2nd law of thermodynamics.

A work input is must to work it in accordance with second law of thermodynamics

Overall cost of ground source heat pump in can range from £20,000–£40,000 cost may vary depending upon additional equipment and efficiency rating of individual parts used.

However once installed it can save upto £1300 every year on electricity consumption bill.

Several countries governments offer financial assistance during setup in order to achieve overall reduced emissions level.

This assistance can bring overall cost down upto some extent. The benefits of installation of GSHP (Ground source heat pump) overweighths cost involved.

Initial setup is costly however after 2-4 years benefits starts to get larger.

There are lots of schemes and programmes in order to promote renewable sources in households in developing countries which helps them to achieve specific target of emissions reduction.

GSHP is overall a benefit over regular electricity consumption methods for households