**5. Results and discussions**

By using the chiller test bench, the following results were obtained for R-22 and R-290 refrigerants.

#### **5.1 Evaluation of R-22 refrigerant in bench tests with chiller**

To perform this test, the bench was initially charged with a load of 910 g of R-22 refrigerant. **Table 5** shows the results obtained with R-22 refrigerant on the chiller test bench.

When using the R-22 refrigerant, the test bench responded by reducing the water temperature by approximately 286.16 K (13°C) within 30 min of operation, where 0.5 kW of electricity was consumed to perform cooling.

For refrigerant R-22, which is known by high discharge temperatures that occur during its use in operation, values around 340.16 K (70°C) were measured, as shown in **Figure 3** that presents the variation in discharge temperature. Usually, these high values are disadvantageous given that they influence lubrication and hence compressor life.

**Figure 3** above shows a large variation in the discharge temperature of the chiller test bench, as a function of operating time. In parallel to the measurement of the discharge temperature variation, the values of the system discharge pressure during operation were also measured, because the higher the temperature of the water to be cooled, the higher the condensing pressure, as can be seen in **Figure 4**, which shows the variation of discharge pressure.

The suction pressure determines at which temperature the refrigerant will evaporate, i.e., the vaporization pressure of the fluid. At the test bench, pressures ranged from 489.52 kPa (71 psig) to 335.08 kPa (48.7 psig), which correspond to the


**91**

refrigerant.

**Figure 4.**

**Figure 3.**

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

*Variation in discharge temperature on test bench using R-22 refrigerant.*

evaporation temperatures of 278.46 K (5.4°C) and 269.16 K (−4.0°C), respectively. During 1 h of operation, the system was able to reduce the temperature and keep the

To perform this, the test bench with chiller was charged with a 370 g load of refrigerant R-290 for 90 min. **Table 6** shows the results obtained with R-290

and recovered, and then leakage was verified in the components of the test bench with nitrogen. Posteriorly, the bench was charged with 370 g of R-290

For the operation of the test bench, the load of R-22 refrigerant was removed

During the tests, it was possible to keep the water temperature close to 274.56 K (1.56°C) and consume 1.0 kW in 70 min of operation. The temperature differences measured at discharge were significantly smaller than those for R-22 refrigerant, as

water between 276.16 K (3°C) and 277.16 K (4°C).

*Variation of discharge pressure on test bench using R-22 refrigerant.*

refrigerant on the chiller test bench.

**5.2 Evaluation of R-290 refrigerant in bench tests with chiller**

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

**Table 5.**

*Test results for R-22 refrigerant on the chiller test bench.*

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

#### **Figure 3.**

*Low-temperature Technologies*

**4.3 Weather conditions**

city of tropical climate.

R-290 refrigerants.

hence compressor life.

shows the variation of discharge pressure.

*Test results for R-22 refrigerant on the chiller test bench.*

test bench.

**5. Results and discussions**

In Belém do Pará, which is a city located in the northern region of Brazil, the season

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

By using the chiller test bench, the following results were obtained for R-22 and

To perform this test, the bench was initially charged with a load of 910 g of R-22 refrigerant. **Table 5** shows the results obtained with R-22 refrigerant on the chiller

For refrigerant R-22, which is known by high discharge temperatures that occur

**Figure 3** above shows a large variation in the discharge temperature of the chiller test bench, as a function of operating time. In parallel to the measurement of the discharge temperature variation, the values of the system discharge pressure during operation were also measured, because the higher the temperature of the water to be cooled, the higher the condensing pressure, as can be seen in **Figure 4**, which

**(kPa)**

**pDesc (kPa) ECons (kW)**

The suction pressure determines at which temperature the refrigerant will evaporate, i.e., the vaporization pressure of the fluid. At the test bench, pressures ranged from 489.52 kPa (71 psig) to 335.08 kPa (48.7 psig), which correspond to the

 303.56 292.76 340.26 309.56 289.66 489.52 1613.37 — 304.16 280.36 340.26 309.66 280.76 380.59 1668.53 12,019 304.26 275.96 341.96 307.96 277.66 351.63 1560.97 12,019 304.36 273.96 331.96 307.56 276.76 335.08 1548.56 12,019 304.66 273.96 327.16 308.46 276.36 344.73 1489.95 12,020

**T1 (K) T2 (K) T3 (K) T4 (K) T5 (K) pSuc**

When using the R-22 refrigerant, the test bench responded by reducing the water temperature by approximately 286.16 K (13°C) within 30 min of operation,

during its use in operation, values around 340.16 K (70°C) were measured, as shown in **Figure 3** that presents the variation in discharge temperature. Usually, these high values are disadvantageous given that they influence lubrication and

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).

**5.1 Evaluation of R-22 refrigerant in bench tests with chiller**

where 0.5 kW of electricity was consumed to perform cooling.

**90**

**Table 5.**

**Time (min)**

*Variation in discharge temperature on test bench using R-22 refrigerant.*

**Figure 4.** *Variation of discharge pressure on test bench using R-22 refrigerant.*

evaporation temperatures of 278.46 K (5.4°C) and 269.16 K (−4.0°C), respectively. During 1 h of operation, the system was able to reduce the temperature and keep the water between 276.16 K (3°C) and 277.16 K (4°C).

#### **5.2 Evaluation of R-290 refrigerant in bench tests with chiller**

To perform this, the test bench with chiller was charged with a 370 g load of refrigerant R-290 for 90 min. **Table 6** shows the results obtained with R-290 refrigerant on the chiller test bench.

For the operation of the test bench, the load of R-22 refrigerant was removed and recovered, and then leakage was verified in the components of the test bench with nitrogen. Posteriorly, the bench was charged with 370 g of R-290 refrigerant.

During the tests, it was possible to keep the water temperature close to 274.56 K (1.56°C) and consume 1.0 kW in 70 min of operation. The temperature differences measured at discharge were significantly smaller than those for R-22 refrigerant, as


#### **Table 6.**

*Test results with R-290 refrigerant on the chiller test bench.*

**Figure 5.**

*Variation in discharge temperature on test bench using R-290 fluid.*

shown in **Figure 5**, which highlights the variation in bench discharge temperature with R-290 refrigerant.

It is observed in **Figure 5** that the maximum discharge temperature measured on the chiller test bench, with R-290 refrigerant, was less than 331.36 K (59°C). The discharge pressure compared to that of R-22 refrigerant showed values up to 29% lower, with little fluctuation, as shown in **Figure 6** that presents the pressure variation in the discharge plumbing.

It was observed that the suction pressure ranged from 317.16 to 344.75 kPa (46 and 50 psig), corresponding to the respective evaporation temperatures of 269.16 K (−4°C) and 271.16 K (−2°C).

When comparing energy consumption, the chiller test bench with R-22 refrigerant consumed 1.0 kW of electricity to cool 40 l of water in 50 min of operation, while with R-290 refrigerant consumed 1.0 kW in 70 min of operation, i.e., with R-22 the bench consumed 1.2 kW/h, while with the R-290 the consumption was 0.857 kW/h.

**93**

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

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

The cooling capacity of system *Q*̇

refrigerant.

**Figure 6.**

and discharge pressure.

(POE) should be used.

(COP) can be calculated as shown in Eq. (1) and Eq. (2):

*Variation of discharge pressure on test bench using R-290 refrigerant.*

**5.3 Comparison between types of refrigerants**

*COPR*−22 = *Q*̇ \_

*COPR*−290 = *Q*̇ \_

 *Ref ECons*

> *Ref ECons*

As calculated above, the R-290 refrigerant COP was 40% higher than of the R-22

The graphs shown below are comparing pressure and temperature of the most common synthetic and natural fluids taken from the Danfoss application [27] and

**Figure 7** shows a comparative graph between these two fluids for temperature

When compared to other refrigerants, R-410A has the highest working pressure, as shown in **Figure 8**, which evidences a comparative graph between dew temperature and operating pressure. Both refrigerants have 0 (zero) ODP, but the GWP is virtually unchanged around 1700, which implies in no advantage in this replacement. Besides that, R-410A has its days counted for discontinuation given the action of laws and

It can be seen from **Figure 8** that R-410A refrigerant has higher cooling capacity and works at higher pressures than R-22 refrigerant. Because this product is not azeotropic, it should always be charged in air conditioning and liquid refrigeration systems. This gas is also not miscible with mineral oils, and therefore polyol-esters

Some comparative studies [20–23] have concluded that R-290 fluid is the natural one with thermodynamic properties more similar to R-22, as shown in **Figure 9**.

based on the National Institute of Standards and Technology (NIST) [28]. As presented in **Tables 4** and **5**, the R-22 substitute refrigerant is R-410A refrigerant. The R-410A is an almost azeotropic mixture composed of R-125 and R-32. It is a chemically stable product with low temperature glide and low toxicity.

According to ASHRAE this fluid is classified as A1 in group L1.

protocols, in order to reduce the environmental pollution [1–3].

= \_2326

= \_2326

Ref was 2326 W, so the performance coefficient

<sup>1200</sup>= 1.9334 (1)

857 = 2.714 (2)

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

**Figure 6.**

*Low-temperature Technologies*

**T1 (K) T2 (K) T3 (K) T4 (K) T5 (K) Psuc**

 305.66 294.26 324.96 306.76 275.66 317.15 1206.58 12,022 305.36 292.16 331.36 309.06 275.36 320.60 1292.76 12,022 306.56 287.96 325.16 307.46 275.36 344.75 1268.63 12,023 306.26 275.96 325.26 307.56 274.86 343.35 1268.63 12,023 306.46 275.26 325.26 307.46 274.86 341.29 1268.63 12,023 306.16 274.96 324.46 307.06 274.36 334.39 1247.95 12,023 305.46 274.66 323.46 306.16 274.66 327.50 1206.58 12,023 305.36 274.16 323.16 306.16 274.66 327.50 1206.53 12,023 304.66 273.76 322.76 305.76 274.76 327.50 1206.53 12,023 305.26 273.76 322.66 305.86 274.66 324.05 1213.48 12,024

**(kPa)**

**PDesc (kPa) Econs**

**(kW)**

**Time (min)**

**Table 6.**

**92**

0.857 kW/h.

with R-290 refrigerant.

**Figure 5.**

tion in the discharge plumbing.

*Variation in discharge temperature on test bench using R-290 fluid.*

*Test results with R-290 refrigerant on the chiller test bench.*

(−4°C) and 271.16 K (−2°C).

shown in **Figure 5**, which highlights the variation in bench discharge temperature

It is observed in **Figure 5** that the maximum discharge temperature measured on the chiller test bench, with R-290 refrigerant, was less than 331.36 K (59°C). The discharge pressure compared to that of R-22 refrigerant showed values up to 29% lower, with little fluctuation, as shown in **Figure 6** that presents the pressure varia-

It was observed that the suction pressure ranged from 317.16 to 344.75 kPa (46 and 50 psig), corresponding to the respective evaporation temperatures of 269.16 K

When comparing energy consumption, the chiller test bench with R-22 refrigerant consumed 1.0 kW of electricity to cool 40 l of water in 50 min of operation, while with R-290 refrigerant consumed 1.0 kW in 70 min of operation, i.e., with R-22 the bench consumed 1.2 kW/h, while with the R-290 the consumption was

*Variation of discharge pressure on test bench using R-290 refrigerant.*

The cooling capacity of system *Q*̇ Ref was 2326 W, so the performance coefficient (COP) can be calculated as shown in Eq. (1) and Eq. (2):

ts shown in Eq. (1) and Eq. (2):

$$
\text{COP}\_{R-22} = \frac{\dot{Q}\_{Rcf}}{E\_{Conv}} = \frac{2326}{1200} = 1.9334\tag{1}
$$

$$E\_{\text{Cous}} \qquad \text{1200}$$

$$\text{LCOP}\_{R-290} = \frac{\dot{Q}\_{Ref}}{E\_{\text{Cous}}} = \frac{2326}{857} = 2.714 \tag{2}$$

As calculated above, the R-290 refrigerant COP was 40% higher than of the R-22 refrigerant.

#### **5.3 Comparison between types of refrigerants**

The graphs shown below are comparing pressure and temperature of the most common synthetic and natural fluids taken from the Danfoss application [27] and based on the National Institute of Standards and Technology (NIST) [28].

As presented in **Tables 4** and **5**, the R-22 substitute refrigerant is R-410A refrigerant. The R-410A is an almost azeotropic mixture composed of R-125 and R-32. It is a chemically stable product with low temperature glide and low toxicity. According to ASHRAE this fluid is classified as A1 in group L1.

**Figure 7** shows a comparative graph between these two fluids for temperature and discharge pressure.

When compared to other refrigerants, R-410A has the highest working pressure, as shown in **Figure 8**, which evidences a comparative graph between dew temperature and operating pressure. Both refrigerants have 0 (zero) ODP, but the GWP is virtually unchanged around 1700, which implies in no advantage in this replacement. Besides that, R-410A has its days counted for discontinuation given the action of laws and protocols, in order to reduce the environmental pollution [1–3].

It can be seen from **Figure 8** that R-410A refrigerant has higher cooling capacity and works at higher pressures than R-22 refrigerant. Because this product is not azeotropic, it should always be charged in air conditioning and liquid refrigeration systems. This gas is also not miscible with mineral oils, and therefore polyol-esters (POE) should be used.

Some comparative studies [20–23] have concluded that R-290 fluid is the natural one with thermodynamic properties more similar to R-22, as shown in **Figure 9**.

#### **Figure 7.**

*Comparative graph between R-22 and R-410A refrigerants. Source: Danfoss [27].*

#### **Figure 8.**

*Comparative graph between the most commonly used refrigerants in Brazil. Source: Danfoss [27].*

Furthermore, it would make it possible to simply replace one fluid to another with less but rigorous modifications to the equipment's electrical system in order to prevent possible fire in case of leakage.

Notwithstanding the similarity with R-22, the R-290 fluid also works at temperatures and pressures close to those of the R-404A, indicating that it can be applied smoothly in these systems, as shown in **Figure 10**.

Between the most commonly used synthetic fluids, it can be seen from **Figure 11** that there is almost a pattern in temperature and pressure variation according to fluid composition.

By observing **Figure 12**, there is remarkable divergence, especially in the case of CO2 due to it is low critical temperature, which does not allow its direct use in air/ water condensation systems such as synthetic fluids.

It is important to note that each type of refrigerant has its applications for each type of air conditioning and refrigeration system and that they should not be mixed, requiring specific procedures for replacing the refrigerant charge.

**95**

**Figure 11.**

**Figure 9.**

**Figure 10.**

*An Experimental Study of Synthetics and Natural Refrigerants Gases*

*Pressure–temperature relation between R-22 and R-290 refrigerants. Source: Danfoss [27].*

*Parameters of synthetic and natural fluids. Source: Danfoss [27].*

*Pressure-temperature relation between azeotropic and zeotropic synthetic fluids. Source: Danfoss [27].*

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

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

*Low-temperature Technologies*

**Figure 7.**

**Figure 8.**

**94**

fluid composition.

Furthermore, it would make it possible to simply replace one fluid to another with less but rigorous modifications to the equipment's electrical system in order to

*Comparative graph between the most commonly used refrigerants in Brazil. Source: Danfoss [27].*

Notwithstanding the similarity with R-22, the R-290 fluid also works at temperatures and pressures close to those of the R-404A, indicating that it can be applied

Between the most commonly used synthetic fluids, it can be seen from **Figure 11** that there is almost a pattern in temperature and pressure variation according to

By observing **Figure 12**, there is remarkable divergence, especially in the case of CO2 due to it is low critical temperature, which does not allow its direct use in air/

It is important to note that each type of refrigerant has its applications for each

type of air conditioning and refrigeration system and that they should not be mixed, requiring specific procedures for replacing the refrigerant charge.

prevent possible fire in case of leakage.

smoothly in these systems, as shown in **Figure 10**.

*Comparative graph between R-22 and R-410A refrigerants. Source: Danfoss [27].*

water condensation systems such as synthetic fluids.

*Pressure–temperature relation between R-22 and R-290 refrigerants. Source: Danfoss [27].*

**Figure 10.** *Parameters of synthetic and natural fluids. Source: Danfoss [27].*

#### **Figure 11.**

*Pressure-temperature relation between azeotropic and zeotropic synthetic fluids. Source: Danfoss [27].*

**Figure 12.** *Pressure-temperature relation between natural fluids. Source: Danfoss [27].*
