Santanu Prasad Datta (Student) P. K. Das & S. Mukhopadhyay

Transcription

1 Effect of Refrigerant Charge, Compressor Speed and Air Flow through the Evaporator on the Performance of an Automotive Air Conditioning System 15 th International Refrigeration and Air July 14-17, 2014 Santanu Prasad Datta (Student) P. K. Das & S. Mukhopadhyay Paper No Mob Indian Institute of Technology Kharagpur Kharagpur India

2 Introduction Automotive Air-Conditioning- A Necessity rather than a Luxury!! Purpose of the Research Variable climate condition Passenger comfort with increasing global warming and pollution Data source: stry_in_india ons/7/7e/satellite_temperatures.png July 16,

3 Introduction Ambient Condition Compressor Speed Automotive HVAC Blower Speed Refrigerant Charge Source: July 16,

4 Background -Automotive Air Conditioning System (AACS) Experiment Limited experiments Steady Mostly steady state performance Stationary Experiments based on stationary system Operating Condition Tests on variation of a limited number of parameters Experiment Steady Stationary Operating Condition System Specific Research on AACS System Specific Parametric range Type of components July 16,

5 Objectives / Goals of the Research with Challenges Experimentally assess the effect of Refrigerant Charge, Compressor Speed and Blower Speed on the performance of the AACS Objective Define a distribution rating parameter to measure the condenser performance by using Infrared Thermography Identify the Optimum Operating Condition Interlinked cycles Diverse working principles Variety of control options July 16,

6 Description of the Test Facility Limitations of the present study Stationary test facility Enhanced tube length to incorporate additional sensor and accessories Avoid temperature or pressure drop across the heat exchangers and additional components July 16,

7 Sensors used in the Test Facility Parameter Type of sensor Location Accuracy Temperature ( o C) T type thermocouple a) Intermediate tube ±0.5 o C a) Surface Thermocouple b) Immersion Thermocouple c) Thermocouple matrix surface b) Immediately before and after main components c) Duct inlet and outlet Condenser and evaporator Bourdon-tube pressure Suction and discharge ±0.25% of full Pressure (Bar) gauge/ pressure transducer line scale Condenser Pressure Drop Differential Pressure Across the condenser ±0.0375% (kpa) Transmitter Refrigerant mass flow rate (kg min -1 ) Coriolis mass flow meter After condenser in liquid line Air flow rate (m s -1 ) Hot wire based airflow Evaporator and transmitter condenser duct Relative humidity Humidity sensor Evaporator duct ±2.0% Compressor speed (rpm) Digital tachometer Along with the motor ±0.025% drive Thermal Image ( o C) Thermal IR imager Condenser surface ±2% ± % of full scale (±0.75% of present reading) ±3.0% July 16,

8 Plan of the Experiments PLAN Test Conditions Condenser Inlet Air Temperature: o C Relative Humidity: 55-60% Evaporator Inlet Air Temperature: o C Relative Humidity: 30-35% Heater Heat Load: 800W Refrigerant Charge (g) Compressor Speed (rpm) Blower Speed (rpm) July 16,

9 Results and Discussion Effect of Refrigerant Charge, Compressor Speed and Blower Speed on the performance of the AACS Refrigerant Mass Discharge Flow Rate Pressure Suction Discharge Pressure Temperature Refrigerant Charge Compressor Speed Blower Speed Suction Press. Discharge Press. Suction Temp. Discharge Temp. Ref. Mass Flow Rate July 16,

10 Results and Discussion Effect of Compressor Speed on Condenser Surface Temperature July 16,

11 Results and Discussion Quantification of the Degree of Non-Uniformity by a Rating Parameter [Bowers et al. (2006; 2010)] Divide the image into M(row) x N(column) pixels T iso Ti M N H i T i Count the number of pixels in each column where, T i T iso H avg H i N N i 1 H i 2NH H avg avg Uniform Non- Uniform July 16,

12 Results and Discussion Condenser Thermal image with the rating parameter (Accuracy of the IR Camera: ±2%) July 16,

13 Results and Discussion Identification the Optimum Operating Condition Refrigerant Charge (m) Compressor Speed (N c ) Blower Speed (N b ),, Uncertainties (Moffat, 1988) Cooling Capacity 1.75% f(engine Compression Work 1.76% f m Speed) COP 4.72% f m 0 COP COP 0 Cooling Capacity Compression Work Cooling Capacity Compression Work COP July 16, max COP rpm m N g b rpm N f (Engine Speed) c

14 Summary Developed a stationary test bench for an Automotive Air Conditioning System Experimentally observed the effect of Refrigerant Charge, Compressor Speed and Blower Speed on the performance of the Automotive Air Conditioning System Attempted to assess a distribution rating parameter to measure the condenser performance by using Infrared Thermography Identified the Optimum Operating Condition Significant Observations Conclusions Effect of Refrigerant Charge and Compressor Speed are severe whereas, Effect of Blower Speed is nominal Heat exchanger is more effectively utilized at higher compressor speed Irrespective of the compressor and the blower speed, a refrigerant charge of 530g gives the optimum performance of the system Applicability This shows the methodology for identifying optimum operating condition Could be a crude step for designing an automatic control July 16,

15 THANK YOU