Greetings

The use of heat pipes as heat exchangers (evaporator and condensator) could drastically improve COP. Depending on the application is the scale of the heat pipe, although costs will increase aswell.

You can go for the hybrid cycle by coupling the heat pipe with conventional cycle improve the cop.  or you may couple dehumidifier using free energy like solar or waster heat for regeneration decreases significantly the air moisture content of cooling air.

Dear Prof Johane Bracamonte,

Thank you for your reply! Actually, I had purchased 1 unit of second-hand air conditioner recently, and I had dismantled it to complete my air-con test rig project. So meaning I could purchase heat pipes and integrate with the air con itself to improve the COP? I'm sorry as I have limited knowledge on this. 

Dear Dr. D.B. Jani,

Thank you for your suggestion! May I know how do I alter the air conditioner cycle? Sorry for my limited knowledge. 

Dear Mr. How,

Heat pipes consists in a tube containing a fluid at saturation conditions (usually at sub barometric or vacuum pressures) and a porous media, sealed at the ends. When a temperature difference is applied at the ends of the tube the fluid evaporates at the hot end and tends to flow to the cold end, where the fluid condensates and flows through the porous media to the hot end due to capillarity effects.

The ends of the heat pipe must be submerged into the heat transfer fluid. In your case one end must be in contact with the HVAC refrigerant and the other end with direct contact with air. This requires that you perforate heat exchangers to weld the heat pipes.

Again this could be very expensive. You should also consider increaing the COP by using a high efficiency compressor. Scroll compressors are about 20% more efficient than stroke compressors.

Best regards

Dear Prof.,

Thank you for your guidance and advises. It really mean a lot to me and my team. Really appreciate it!

Have a nice day!

Best regards 

I would advice adding to the above suggestions that you should think of proper cooling of condenser. May be spraying water over it will clean its surface from dust and will evaporatively cool it far better and will render an efficient cycle of operation.

The following literature may be useful for your research

Heat pipes are heat transfer devices that enhances large amount of heat which works on the principle of evaporation and condensation of a working fluid. Inspite of wide application of heat pipe in microelectronics cooling system the trend of the

chips performance and power utilization has been increased each year and a complete understanding of mechanism has not yet been completed even though it has the ability to operate against gravity and a greater maximum heat transport capability.

Termal resistance and heat transfer capability of heat pipe are affected by the choice of working fluid, the tilt angle, the fill ratio, thermal properties and heat input. 

Ref: www.technicaljournalsonline.com/.../ARTICLE%2006%20APRIL%20JU

Thermal efficiency of heat pipe is further increased by adding nano fluids

www.sciencedirect.com/science/article/pii/S0925838810002604

COP of Air refrigeration system, which works on Bell Coleman cycle depends on heat absorbed and workdone on system. Either heat absorbed is to be increased or workdone on the system is to be reduced in order to have higher COP. Better option isto reduce workdone on the system. It depends on design of compressor and condensor.

In case of COP of AC system, ( which is simultaneous control of temperature, humidity, air quality and air motion) other parameters also will come into pitcture.

like area of the room, oreintation of room, application, seating capacity,  equipment used in the room, latent heat load, sensible heat load, outside condtions like DBT, WBT,humidity etc., design condition, by pass factor of heating or cooling coil, inflitration, season, volume of the air inhaled per minute, type of AC sysem installed like split AC or Window AC, Method of AC like cetnral AC system etc.,.

However, main concentration is to reduce workdone on compressor. Latest techniques are addition of nano particles, and  use of heat pipes as suggested ny Prof. Johane.    .   

Thanks everyone for your reply!

There are some new refrigerant are studying in many laboratories which might give you better performance if you use it in an existing system. These are very much environment-friendly.  

The COP can be increased by controlling the operating condition such as condensing temperature or by making physical changes such as adding a heat exchanger, replacing the refrigerant, ...For an existing system, I suggest to reduce the condensing temperature by integrating an evaporative cooler to cool air before going to condenser. This can give a significant enhancement.

In addition to the suggestion made above, I like you to to introduce diffuser that will reduce the compressor work and enhance the COP.

I recommend using a variable speed compressor( an inverter one) which is proved recently to save a lot in energy consumption.