Heat pump technology has been rapidly developed recently as a clean and efficient heating method. Continuous capacity modulation of heat pumps is necessary for enhancing room thermal comfort and reducing start-stop losses. A novel capacity modulation method for the scroll compressor heat pump system based on refrigerant injection and refrigerant release is proposed. The experiments indicate the...

The TEWI analysis of residential heat pumps shows that it is sensitive to refrigerant emissions and mainly dependent on the seasonal coefficient of performance of the heating unit. Otherwise for countries where electricity is mainly produced by a combination of nuclear-power and hydro-power, the direct emissions become not negligible compared to the indirect emissions. Both direct and indirect ...

The capillary tube/suction line heat exchanger (SLHX) is widely used in small refrigeration systems. The refrigerant flowing in the SLHX experiences frictional and accelerational head losses, flashing, and heat transfer simultaneously. The simulation of refrigerant flow through SLHX is important since this will help engineers analyze and optimize the SLHX incorporated in a refrigeration system....

The present paper summarizes the activities at LTT-Erlangen on the field of thermophysical properties research for pure refrigerants and refrigerant mixtures. For the characterization of their thermophysical properties dynamic light scattering (DLS) has been intensively applied as a key tool during the past two decades. Beside a representation of the essential features of DLS for the determinat...

The Air conditioning system satisfies the various space conditions required for the comfort and industrial air conditioning. Now days demand for AC system applications are increasing and include the areas of application like apartment buildings, banks, office buildings, industrial plants, schools, restaurants etc. This growing demand for air conditioning system forced manufactures to develop su...

Kim, Woohyun. Ph.D., Purdue University, December 2013. Fault Detection and Diagnosis for Air Conditioners and Heat Pumps based on Virtual Sensors. Major Professor: James E. Braun, School of Mechanical Engineering. The primary goal of this research is to develop and demonstrate an integrated, on-line performance monitoring and diagnostic system with low cost sensors for air conditioning and heat...

Selection of spiral capillary tube for refrigeration appliances and the effect of changes in the parameters such as capillary tube dimensions i.e. capillary tube diameter, coil pitch, capillary tube length and inlet conditions of refrigerant to the capillary tube i.e. degree of subcooling, inlet pressure on the mass flow rate of the refrigerant, also investigation about the coiling effect of sp...

The errors associated with therModynamic performance calculations are discussed with particular reference to systems with a high oil charge. It is shown that calculations made using published refrigerant data can be very misleading as no account is taken of the oil solubility effects. Pressure-enthalpy charts are presented for refrigerant R12 oil mixtures, for a range of oil concentrations. The...

This work presents an experimental approach to study the refrigerant flow through capillary tube-suction line heat exchangers. Lateral heat exchanger performance with refrigerant HFC-134a was experimentally evaluated for a range of heat exchanger assemblies and operating conditions typically found in household refrigerators and freezers. Based on the resulting performance data base, the influen...

Models for unitary air conditioners and heat pumps typically have difficulties in providing accurate predictions for the following situations: 1) charge modeling over a large range of charge levels, 2) two-phase refrigerant entering fixed-orifice expansion devices, 3) two-phase refrigerant entering compressors, and 4) non-uniform refrigerant mass flow allocation among evaporator circuits at low...