**4. Test bench type chiller**

In this topic, the theoretical foundations about vapor compression type cooling systems, with synthetic and natural fluids, necessary for the understanding about the experimental apparatus used are initially approached. After that, the experimental apparatus developed in the ClimatCont laboratory to simulate a chiller system has been described.

#### **4.1 Theoretical fundamentals**

Some scientific studies specifically dedicated to the comparison of natural fluids with the most common synthetic ones, such as R-22 fluid, have been carried out and published. The research conducted by Park and Jung's [20] related the replacement

of R-22 with R-290 with the need of electrical adaptations to ensure the safety of the installation, which resulted in performance coefficients (COP) up to 11.5% when compared to the R-22, i.e., the system with R-290 required 11.5% less electrical power to generate the same refrigeration capacity. Another important point was the reduction of compressor discharge temperatures, which were reduced from 358.16 K (85°C) to 338.16 K (65°C), indicating better use of the lubricant life [20].

Sharmas and Babu comparatively analyzed mixtures between HC and HFC in relation to their characteristics as refrigerants, observing that mixtures containing HCs provided the system with a COP up to 2% higher than a system with HFC, also reducing the compressor discharge temperature, up to 295.16 K (22°C), and for the HCs mixture, a reduction of up to 1 kW per cooling tons in electric power consumption had been achieved [21]. In a computational analysis, these authors assessed that the HC mixture provided a COP of 5.35% over R-22, plus 286.16 K (13°C) lower discharge temperature for the same fluid and with reduced electrical power consumption by 5% [22].

Agrawal et al. compared a mixture of HC (R-290 and R-600a) with HFC (R-134a) and found that the optimum charge for the mixture was 60 g, less than half of the original charge 140 g of HFC, and the nearly 40% improvement in COP. With the optimum loads, HFC consumed 0.5 kW/h, and the HC mixture consumed 0.4 kW/h, providing the cooling capacities of 70 W and 76 W, respectively [23].

#### **4.2 Chiller test bench**

To carry out a practical analysis of the use of types of refrigerants, a test bench with a chiller was developed at the Federal University of Pará (UFPA) in partnership with the Refrigeration and Climatization and Thermal Comfort Laboratories (ClimaTConT) along with the research group "Resfriar Project," from the Energy, Biomass and Environment Group (EBMA). The main purpose of the bench is to create a demonstration of the operation of the refrigeration cycle, considering the local psychometric conditions, with a variety of refrigeration fluids.

In this test bench, all parameters are controlled and components have been assembled to facilitate understanding of fluid behavior and performance. After doing a research in the technical literature and articles on refrigerants and their properties and characteristics as environmental contaminants, the conclusion was that the bench will be a good system for a comparison between the original working fluid, HCFC R-22, and natural fluids, hydrocarbon base, which after investigation of the negative points of natural fluids, were the best suited to the project conditions [17, 24].

The test bench is composed of a condenser unit Elgin TUM-2053E 220 V, 60 Hz, single phase, with 1.6 kW of cooling capacity and power consumption of 880 W, with R-22 fluid and with a 1.5 l capacity liquid tank. The expansion device is a Thermostatic Expansion Valve from Danfoss, model TX2, for R-22, with number 01 orifice, with a maximum capacity of 2.5 kW and a single evaporator made of cooper tube with 3/8" of diameter and 1/16" of thickness, contained in an insulated box that can hold until 45L of water as shown in **Figure 1**.

Systems that use water as a refrigerant can both remove heat and add heat of an ambient making the environment conditioned. Refrigerant circulates inside pipes between the heater and the cooler. These systems can be classified according to operating temperature, flow type, and degree of pressurization [25].

The chilled water system is a type of cooling system that operates with water being a secondary fluid in the temperature range of 277.16 K (4°C) to 286.16 K (13°C), usually between 279.16 K (6°C) and 280.16 K (7°C), with working

**89**

environments [26].

**Figure 2.**

**Figure 1.**

characteristics similar to HCFC.

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

pressure close to 800 kPa as presented in **Figure 2**, which shows a schematic of the test bench stand with a chiller, which must be used for the cooling of

*Schematic representation of the chiller cooling cycle. Source: ASHRAE Fundamentals (adapted) [16].*

Preliminary data observed from the test bench with chiller shows that its working pressure is 310.26 kPa (45 psig), which indicates an evaporation temperature of 267.16 K (−6°C); considering the Δ*T* of 283.16 K (10°C), the fluid is cooled to 279.16 K (6°C). In this way, the bench tests consisted of evaluating the energy consumption of the R-22 fluid operation, in addition to the working temperatures at specific points, with the values of the refrigerant R-290, which is the fluid with

To measure the temperature parameters, five-point thermometers were installed

that acquired the following temperatures: T1, for room temperature; T2, for the temperature in the suction pipe; T3, for the temperature in the discharge pipe; T4, for condenser air outlet temperature; and T5, for water temperature. For the measurement of pressure values in the suction (pSuc) and discharge (pDesc) lines of the compressor, a digital pressure gauge was installed in the respective test bench pipes. The energy consumed (ECons) during the tests was acquired by a power meter

installed on the chiller test bench electrical system, as shown in **Figure 1**.

*DOI: http://dx.doi.org/10.5772/intechopen.89119*

*Bench tests with chiller mounted by ClimaTConT.*

*An Experimental Study of Synthetics and Natural Refrigerants Gases DOI: http://dx.doi.org/10.5772/intechopen.89119*

#### **Figure 1.**

*Low-temperature Technologies*

respectively [23].

tions [17, 24].

**4.2 Chiller test bench**

of R-22 with R-290 with the need of electrical adaptations to ensure the safety of the installation, which resulted in performance coefficients (COP) up to 11.5% when compared to the R-22, i.e., the system with R-290 required 11.5% less electrical power to generate the same refrigeration capacity. Another important point was the reduction of compressor discharge temperatures, which were reduced from 358.16 K (85°C) to 338.16 K (65°C), indicating better use of the lubricant life [20]. Sharmas and Babu comparatively analyzed mixtures between HC and HFC in relation to their characteristics as refrigerants, observing that mixtures containing HCs provided the system with a COP up to 2% higher than a system with HFC, also reducing the compressor discharge temperature, up to 295.16 K (22°C), and for the HCs mixture, a reduction of up to 1 kW per cooling tons in electric power consumption had been achieved [21]. In a computational analysis, these authors assessed that the HC mixture provided a COP of 5.35% over R-22, plus 286.16 K (13°C) lower discharge temperature

for the same fluid and with reduced electrical power consumption by 5% [22]. Agrawal et al. compared a mixture of HC (R-290 and R-600a) with HFC (R-134a) and found that the optimum charge for the mixture was 60 g, less than half of the original charge 140 g of HFC, and the nearly 40% improvement in COP. With the optimum loads, HFC consumed 0.5 kW/h, and the HC mixture consumed 0.4 kW/h, providing the cooling capacities of 70 W and 76 W,

To carry out a practical analysis of the use of types of refrigerants, a test bench with a chiller was developed at the Federal University of Pará (UFPA) in partnership with the Refrigeration and Climatization and Thermal Comfort Laboratories (ClimaTConT) along with the research group "Resfriar Project," from the Energy, Biomass and Environment Group (EBMA). The main purpose of the bench is to create a demonstration of the operation of the refrigeration cycle, considering the

In this test bench, all parameters are controlled and components have been assembled to facilitate understanding of fluid behavior and performance. After doing a research in the technical literature and articles on refrigerants and their properties and characteristics as environmental contaminants, the conclusion was that the bench will be a good system for a comparison between the original working fluid, HCFC R-22, and natural fluids, hydrocarbon base, which after investigation of the negative points of natural fluids, were the best suited to the project condi-

The test bench is composed of a condenser unit Elgin TUM-2053E 220 V, 60 Hz, single phase, with 1.6 kW of cooling capacity and power consumption of 880 W, with R-22 fluid and with a 1.5 l capacity liquid tank. The expansion device is a Thermostatic Expansion Valve from Danfoss, model TX2, for R-22, with number 01 orifice, with a maximum capacity of 2.5 kW and a single evaporator made of cooper tube with 3/8" of diameter and 1/16" of thickness, contained in an insulated box

Systems that use water as a refrigerant can both remove heat and add heat of an ambient making the environment conditioned. Refrigerant circulates inside pipes between the heater and the cooler. These systems can be classified according to

The chilled water system is a type of cooling system that operates with water being a secondary fluid in the temperature range of 277.16 K (4°C) to 286.16 K (13°C), usually between 279.16 K (6°C) and 280.16 K (7°C), with working

local psychometric conditions, with a variety of refrigeration fluids.

that can hold until 45L of water as shown in **Figure 1**.

operating temperature, flow type, and degree of pressurization [25].

**88**

*Bench tests with chiller mounted by ClimaTConT.*

#### **Figure 2.**

*Schematic representation of the chiller cooling cycle. Source: ASHRAE Fundamentals (adapted) [16].*

pressure close to 800 kPa as presented in **Figure 2**, which shows a schematic of the test bench stand with a chiller, which must be used for the cooling of environments [26].

Preliminary data observed from the test bench with chiller shows that its working pressure is 310.26 kPa (45 psig), which indicates an evaporation temperature of 267.16 K (−6°C); considering the Δ*T* of 283.16 K (10°C), the fluid is cooled to 279.16 K (6°C). In this way, the bench tests consisted of evaluating the energy consumption of the R-22 fluid operation, in addition to the working temperatures at specific points, with the values of the refrigerant R-290, which is the fluid with characteristics similar to HCFC.

To measure the temperature parameters, five-point thermometers were installed that acquired the following temperatures: T1, for room temperature; T2, for the temperature in the suction pipe; T3, for the temperature in the discharge pipe; T4, for condenser air outlet temperature; and T5, for water temperature. For the measurement of pressure values in the suction (pSuc) and discharge (pDesc) lines of the compressor, a digital pressure gauge was installed in the respective test bench pipes. The energy consumed (ECons) during the tests was acquired by a power meter installed on the chiller test bench electrical system, as shown in **Figure 1**.

#### **4.3 Weather conditions**

In Belém do Pará, which is a city located in the northern region of Brazil, the season with precipitation is overcast, and the dry season is partly cloudy. The city is surrounded by the Guamá River, which is responsible for the high rainfall index of the city.

All year round, the climate of Belém is hot and with high thermal sensation. Throughout the year, the average temperature generally ranges from 297.16 K (24°C) to 309.16 K (36°C), with a relative air unit that is approximately 90%. This city has a thermal sensation ranging from 307.16 K (34°C) to 319.16 K (42°C).

The average altitude of Belém do Pará ranges from 0 to 20 m above sea level, with average barometric pressure of 1010.28 kPa. In summary, Belém do Pará is a city of tropical climate.
