Case Study

Bluon TdX 20 Compared to R-22
Testing Summary
Prepared by
PG&E Applied Technology Services
Prepared for
Bluon Energy
August 2015
Testing Summary
Bluon TdX 20 has been formulated as a drop-in replacement for R-22 in existing equipment. Rather than a pure
chemical like R-22, Bluon TdX is a proprietary blend of several constituents each of which have been approved
under the Environmental Protection Agency’s SNAP (Significant New Alternatives Policy) program. Bluon TdX 20,
has been evaluated by the EPA and is currently authorized, under rule Section 82.180, for sales in commercial and
residential air conditioning and heat pump systems. The use of a drop-in replacement will allow customers to
operate their existing air conditioning and refrigeration equipment farther into the future.
Testing was performed under contract from Bluon Energy to provide them with a report comparing TdX 20 with
R-22. The test was performed in a controlled environment in the HVAC testing apparatus at PG&E’s San Ramon
(California) Technology Center. The HVAC apparatus consisted of two side-by-side environmental chambers
designed according to ASHRAE Standard 37.
The objective of the test was to compare the efficiency of an air conditioner unit with the only variable being the
type of refrigerant in the circuit. Tests were conducted on the system across different outside air temperatures
and using both one and two compressors to isolate just the effect of the refrigerants. The test results are
summarized below in the following figures and tables.
Energy Efficiency Measures Summary
EER is depicted at the AHRI Standard Test A with conditions of 95⁰F outside air temperature; SEER as calculated by the weighted bin method;
and IEER derived from the AHRI Standard Test A with single compressor operation at temperatures between 65⁰F and 72⁰F.
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Test Comparisons TdX 20 v R-22 Summary
Bluon TdX 20 showed better efficiency and lower pressures and temperatures as compared to R-22 across
different outside air temperatures, using both one and two compressors. The results are demonstrated in the
tables below1.
The testing unit was a Carrier Single-Package Rooftop Unit – Model 48 DJDE009 – 8.5 Nominal Tons, 2 Circuits, and 2
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1. ANSI/AHRI Standard 210/240-2008, Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump
Equipment, Air-Conditioning, Heating and Refrigeration Institute, 2111 Wilson Boulevard, Suite 500, Arlington,
VA 22201, 2011. pdfs/ANSI standards
pdfs/ANSI.AHRI Standard 210.240 with Addenda 1 and 2.pdf
2. ANSI/AHRI Standard 340/360-2007, Performance Rating of Commercial and Industrial Unitary Air-Conditioning
and Heat Pump Equipment, Air-Conditioning, Heating and Refrigeration Institute, 2111 Wilson Boulevard, Suite
500, Arlington, VA 22201, 2011. pdfs/ANSI
standards pdfs/ANSI AHRI Standard 340-360-2007 with Addenda 1 and 2.pdf
3. ANSI/ASHRAE Standard 37-2009, Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and
Heat Pump Equipment, ASHRAE, 1791 Tullie Circle NE, Atlanta, GA 30329, 2009.
4. Davis, Robert, Laboratory Testing of Performance Enhancements for Rooftop Packaged Air Conditioners,
This report was prepared by Pacific Gas and Electric Company. Neither Pacific Gas and Electric Company nor any
of its employees and agents:
1) makes any written or oral warranty, expressed or implied, including, but not limited to those concerning
merchantability or fitness for a particular purpose;
2) assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information,
apparatus process, method, or policy contained herein; or
3) represents that its use would not infringe any privately owned rights, including, but not limited to, patents,
trademarks, or copyrights.
Test Objectives
The objectives of this test was to compare various performance attributes of an air conditioner with only variable
being the type of refrigerant in the circuit. Tests were conducted on the system at a fixed set of environmental
conditions and operating modes to isolate just the effect of the different refrigerants. The key parameters of interest for
Bluon were:
Cooling Capacity
Power Consumption
Efficiency (EER, SEER, IEER, COP)
Suction Pressure
Discharge Pressure
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Discharge Temperature
Compressor Head Temperature
Mass Flow Rate
Ramp-up Time
Laboratory Facility
All testing was performed in the HVAC testing apparatus in the Advanced Technology Performance Lab (ATPL) at
PG&E’s San Ramon Technology Center. The apparatus consists of two side-by-side environmental chambers designed
according to ASHRAE Standard 37 (reference 3). The two chambers have independent conditioning systems for
maintaining temperature and humidity, and each has its own airflow measurement apparatus or “code tester”. The
airflow measurement apparatus follow ASHRAE standard design, and consist of a sealed box with a partition having
several flow nozzles that can be opened or sealed in combination to provide the required range of differential pressure
for the current airflow. Variable-speed blowers on the outlets of each station can be set to maintain the desired outlet
static pressures or airflow rates and compensate for the added resistance of the flow measurement system and
ductwork. The smaller of the two chambers is conditioned to maintain the required return air conditions to the RTU and
its code tester is used to measure the supply airflow from the RTU. Whereas the larger chamber is used to maintain the
required outside air conditions to the RTU condenser and its code tester is used to measure the condenser exhaust
airflow. The test air conditioner was located completely inside the large chamber.
Figure 1: HVAC Test Lab
(Indoor room on left, outdoor room on right)
Test Unit
The air conditioner used for this evaluation is a circa 1991 Carrier Model 48DJD009 rooftop unit (RTU) with a
nominal capacity of 8½-tons (100,000 Btu/hr). The unit is equipped with two compressors operating with R-22
refrigerant, a fixed-speed (constant volume) 1½-hp indoor blower, and a single ¾-hp condenser fan interconnected with
the first stage compressor. The reason this unit was chosen was because it was already set up and instrumented in the
PG&E HVAC laboratory following testing work that lead to the report listed as Reference 4. It has the advantage of being
a fairly good representative of the state of existing systems. One drawback to using this unit was that with two
compressors there are two separate circuits that would need to have the refrigerant replaced, increasing the cost and
time required. Another issue is that the system uses what Carrier calls an Acutrol™ metering device, which is basically a
header with multiple fixed orifices feeding separate circuits in the evaporator. If some become fouled, then the
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evaporator may end up out of balance. Also, like most fixed geometry expansion devices, the system is less forgiving of
improper refrigerant charge than one with a modulating expansion device like a TXV.
Only a few modifications were needed to the test unit following the previous work. The outside air economizer was
removed and a panel was installed in its place to prevent any intake of outside air. Thermocouples were attached to the
top center of the two compressors to measure their head temperature, and two pressure transmitters were attached at
the compressor discharges in addition to the existing transmitters at the compressor suction and condenser outlet of
both circuits.
Test Procedure
The test procedure was nearly identical for each refrigerant charge, with some excursions. The return air to the test
unit was held consistently at 80°F dry-bulb, and usually at 67°F wet-bulb (or about 50% relative humidity) following the
condition used for rating purposes in the AHRI Standards (References 1 and 2). Some tests required a dry coil, for which
the humidifier was turned off and the return air humidity was allowed to drop to whatever the ambient dew point
would allow. (Usually around 61°F wet bulb, but still above the 57°F recommended in the standards.) The indoor fan
was active at its fixed speed throughout the tests, with a supplemental fan and variable damper on the return duct set
to maintain zero static pressure relative to the outside room at the return air intake, and with the variable speed
booster fan on the airflow measurement device set to maintain a static pressure rise across the test unit (supply –
return) of 0.25 inches of water. When the condenser fan was active, the variable speed fan on the exhaust airflow
measurement device was set to maintain zero static pressure in the duct attached to the top of the RTU to capture the
exhaust flow.
Most of the system charging was done with the outdoor room temperature set at 82°F, which is the AHRI 210/240
Standard condition for test “B”. This was mainly done for the comfort of the service technician, as opposed to the “A”
test condition of 95°F. Charge was initially added by weight, and then adjusted as needed to obtain the desired
superheat for each circuit. Between charge changes, the previous refrigerant was recovered and the filter/driers were
replaced. The circuits were charged with nitrogen at moderate pressure and held there to confirm no leakage, and then
the circuits were pulled down to a low vacuum and held there to evaporate any liquid in preparation for adding the new
refrigerant. The service technician was contracted directly by Bluon, and was well acquainted with system charging with
their refrigerant.
The superheat for each circuit was watched both by the technician’s tools and through the test data acquisition
system, which used calls to NIST’s REFPROP library to look up properties for the different refrigerant blends and plot a
live P-H diagram on the screen, along with calculated values of suction superheat and condenser subcooling. A sample
screenshot of the data acquisition program is shown in Figure 2.
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Figure 2: Example DAS System Screenshot
A script was formulated to run the lab through the same test sequence with each refrigerant, which allowed for
tests to be run overnight and unattended. Once the charge quantity was settled and enough time had passed such that
condensate was observed to be draining from the evaporator coil, the data collection system was set to begin logging
the data readings, normally at a 10-second interval. There were several distinct phases in the script:
Phase 1: AHRI Standard Test “B”
The outdoor room was held at the starting 82°F for 45 minutes, from which the last 30 minutes would be
used for data analysis.
Phase 2: Outside Temperature Ramping
The intent of this phase was to map the system performance as a function of the outdoor temperature. The
temperature in the outdoor room would be ramped up or down at a rate of 1°F every two minutes to the
next set point, and then held there for 45 minutes at most points. The selected set points ranged from a low
of 65°F to a high of 115°F in 10°F increments (65, 75, 85, 95, 105, and 115). The script ran through the set
points in a sine-wave pattern, beginning at the first stop of 85°F, rising up to 115°F, then down to 65°F, and
then back up to 80°F. This hit all of the intermediate temperatures twice (including AHRI Standard Test “A”
at 95°F), but the extremes (including the AHRI Standard and the Maximum Operating Condition Test at
115°F) only once. For those two points, the steady-state period was extended to 1 hour to ensure stability.
Phase 3: Single Compressor Operation
At the conclusion of the last phase, the second compressor in the RTU was shut off and the outside
temperature was nudged up to 81.5°F and the system held there for 1 hour. The purpose of this test was
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primarily to capture part-load performance for use in calculating an IEER per AHRI Standard 340/360
(Reference 2; see example 3). Subsequent tests were run at outside temperatures of 68°F and 65°F, and in
some cases at 71°F, with just the one compressor.
The operation with only one compressor also allows for a calculation of an approximate refrigerant mass
flow rate through that one circuit since it was not being measured directly. The refrigerant mass flow is
calculated by taking the measured air-side cooling capacity (which is only being provided by the one circuit),
adding back in the indoor fan power (since the fan power reduces the cooling done by the coil alone), and
then dividing by the enthalpy change of the refrigerant across the coil, as follows:
𝑚̇ (𝑙𝑏⁄𝑚𝑖𝑛) =
12,000 ×𝑇𝑜𝑛𝑠+3,412 ×𝐵𝑙𝑜𝑤𝑒𝑟 𝑘𝑊
ℎ𝑠𝑢𝑐𝑡𝑖𝑜𝑛 −ℎ𝑙𝑖𝑞𝑢𝑖𝑑
÷ 60
Equation 1
Phase 4: Dry Coil Tests
At this point, the humidifier in the indoor room controlling the return air wet-bulb temperature was turned
off, the second compressor was turned back on, and the outdoor room temperature was ramped back up to
82°F at the same rate as before. The low-temperature operation with both compressors helped to wring out
much of the remaining moisture in the air along with drawing in some outside air; and by the time the
outdoor room reached the set point, the flow of condensate from the evaporator coil had ceased. The
system was then held steady at 82°F for an hour to capture AHRI Standard Test “C”.
Following the steady-state period began a series of cyclic tests. The AHRI Standard cycle is 24 minutes off
followed by 6 minutes on. For these tests, the AHRI Standard procedure was deviated from in that the
indoor blower was kept on with only the compressors cycled, and the two compressors were cycled
together as if they were one (although a 10-second delay between the starts of the first and second
compressor was added so as not to overload the circuit with startup current.) For most of the tests, three
sequential cycles were conducted, with the third used for data analysis. For some of the sequences, the
cyclic tests were expanded to include more realistic cycling: first where the secondary compressor was
cycled with the primary compressor always on, and second where the primary compressor was cycled with
the secondary compressor off. Since this was not done consistently for each of the refrigerant charges, they
have not been included in the analysis.
The test sequence ended at the end of the cyclic tests.
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