Experimental data for an air-conditioning system identification

In this article, data from a 3.5kW mini split air conditioning is presented. A screening 23 design experiment was performed to evaluate the effects of indoor air temperature, absolute humidity and evaporator fan speed in the performance of the air conditioning. This dataset also includes noise factors as outdoor air temperature, fans energy consumption and response as indoor air exit conditions.


Data
This paper presents the experimental data obtained from a 2 3 screening design experiment. The experiment was performed to evaluate the effects of the inlet temperature and inlet humidity of the indoor air, and evaporator fan speed on the performance of a mini split air-conditioner. The system consists of a 3.5kW cooling capacity mini split with inverter and a seasonal energy efficiency ratio of 17, in this system, 21 sensors were installed in order to measure refrigerant, air, and current data. Data describe the inlet and outlet conditions of indoor and outdoor air (temperature and relative humidity), refrigerant R410A (temperature, pressure, volumetric flow) and power consumption (current) of the equipment, Table 1 shows the description and location of each sensor. Each run was performed at steady state operation for 1 hour and 45 minutes. To assure steady state, measurements started 1 hour after the air conditioning startup or change in the air inlet conditions as recommended in ASHRAE/ AHRI 210 [1] and ISO 5151 standards [2]. Fig. 1 shows the experimental test rig scheme; it is localized in the Universidad del Norte, Barranquilla Colombia. Barranquilla is a tropical climate city, whose mean annual outdoor air temperature is in the range from 24 C to 30.1 C; besides, the annual mean outdoor air relative humidity is in the range from 80 to 85%. To assure indoor air inlet conditions in the evaporator, an air hood was installed at evaporator air inlet; using an electrical heater, and/or a steam generator (depending on the situation) to maintain the inlet conditions at the accepted range during the time measurements. Table 1 shows the description of each sensor installed in the test rig.

Experimental design, materials and methods
Considering that this is not a standard test, the accuracy of each sensor is accepted as recommended by the US Department of Engineering [3], temperature of indoor air at the evaporator inlet was stablished in 23 C and 28 C with ±1 C as an acceptable range, which represents the typical range of indoor air temperature in rooms and offices. In the other hand, the absolute humidity is not directly measured; hence, relative humidity is adapted to reach the required values. Nevertheless, the relative humidity also depends on the air temperature, so to reach the 2 absolute humidity accepted values, 4 values of relative humidity are required, in Table 2 the values are presented.
The evaporator fan has 3 velocity levels and 1 auto mode; during the experimental tests, the evaporator fan speed was recorded as categorical data. Actual air speed was not measured; however, this factor was considered as it might influence results (i.e. outlet air temperature at evaporator). Two Specifications Table   Subject area Mechanical Engineering More specific subject area Refrigeration and air-conditioning Type of data Excel files How data was acquired Experimental data obtained from a 3.5kW mini-split air-conditioning system using R410A as refrigerant. The instrumentation used was: (10) Digital thermometers Maxim DS18B20 ( ± 0.5 C accuracy) (4) Pressure transducers Full Gauge Controls SB69 ( ± 1psig error) Before any experimental test, electrical wires connections were checked.

Experimental features
The experimental tests were conducted in a 3.5kW mini-split air-conditioning system (see Fig. 1). The inlet temperature and inlet humidity of the indoor air, and evaporator fans speed were manipulated. The following variables were measured: outlet temperature and outlet humidity of the indoor air, temperature and pressure of the refrigerant, electrical currents of the compressor and evaporator fans, and inlet and outlet temperatures of the outdoor air.

Data source location
Laboratorio de Termofluidos, Universidad del Norte, Barranquilla, Colombia Data accessibility Data is with this article.
Value of the data A detailed database for the steady-state response of a 3.5kW mini-split air-conditioning system in a tropical climate zone. This unique multivariate experimental design and data collection consider 3 factors that potentially influence the performance of a 3.5kW mini-split air-conditioning system in a tropical climate zone. The data can be used by other researchers to carry out models validations, by providing a common benchmark. This data can be used to comparing the performance of the air-conditioning system with the performance obtained in other climate zones.
(2) Fan speed levels were chosen in this experiment (low-level speed and high-level speed). Based on Table 2 data, a fan level, indoor air temperature, and indoor air relative humidity level experimental design was performed; to assure homogeneity in the results, the running order for the test were randomized. Dataset is stored in an Excel file, with 16 worksheets, one for each experimental test. The first column for each worksheet shows the time elapsed between the first and the given measured data; date is not included in the data because the acquisition unit doesn't capture the date time. The data for Table 1 Instrument location and reference.

Reference
Description Precision/Accuracy T1 Refrigerant temperature at compressor inlet ±0.5 C T2 Surface temperature of the compressor ±0.5 C T3 Refrigerant temperature at compressor outlet ±0.5 C T4 Outdoor air temperature at condenser inlet ±0.5 C T5 Outdoor air temperature at the condenser outlet ±0.5 C T6 Refrigerant temperature at condenser ±0.5 C T7 Refrigerant temperature at condenser outlet ±0.5 C T8 Surface temperature of the Capillary tube ±0.5 C T9 Indoor air temperature at the evaporator inlet ±0.5 C T10 Indoor air temperature at the evaporator outlet ±0. all the 21 measurements are presented resulting in 10700 store data, a mean of 6700 data per run. The absolute pressure data was calculated by the addition of the gauge pressure measurement from the experimental system and the atmospheric pressure (at sea level ¼ 14.7 PSIa). Calculated power consumption is the product of current data measure from the experimental system by voltage (120V). Finally, Table 3 shows the order of the running test and the indoor air inlet conditions for each test.