Performance evaluation of an indirect-direct evaporative cooler using biomass-based packing material

Figures & data

Figure 1. Working principle of indirect-direct evaporative cooler.

Figure 2. (a) Indirect cooler (b) Celdek Packing (c) Coconut coir packing.

Figure 3. Photo of the experimental setup.

Table 1. Instrument specification; Kumar et al.(2023).

Component	Specifications
Hygrometer	Make/Model	UNI – T UT333
	Humidity range	0–100%
	Resolution	0.1% R.H
	Accuracy	±5%
Anemometer	Make/Model	Work zone AVM − 03
	Wind velocity	0–45 m/s
	Temperature	0 – 45oC
	Resolution	0.1 m/s
	Accuracy	±3%
Digital temperature indicator	Make/Model	Digiqual systems 301
	No. of selectors	6
	Type	K - type
	Range	0–199.9 C
	Resolution	0.1°C
Thermocouple	Type		Chromel – Alumel (K-type)
	Operating temperature range		0–200°C
	Accuracy		±2.2oC of 0.75%
Digital Thermometer	Make/model Range Material	BEETECH T P 1 0 1 −50°C to 300°C ABS
Dimmer stat	Range Power	0 – 270V 1KW

Table 2. Variation of operating conditions.

	Entry Air velocity (m/s)	Air velocity after the air channel (m/s)	Water flow rate (LPM)
Celdek Packing	3.3	2.7	1
	4.2	3.5	2
	5	4.2	3
	6	5	4
Coconut coir packing	3.3	2.7	1
	4.2	3.5	2
	5	4.2	3
	6	5	4

Table 3. Error values for output variables.

Sl. No	Output variables	Percentage error
1	Evaporation rate	1.69
2	Cooling effect	2.73
3	Wet bulb effectiveness	3.24

Figure 4. Variation of DBT ratio with the air velocity and water flow rates for different configurations.

Figure 5. Variation of RH ratio with the air velocity and water flow rates for different configurations.

Figure 6. Variation of Wet bulb effectiveness with the air velocity and water flow rates for different configurations.

Figure 7. Pressure drop variation with the air velocity and water flow rates for different configurations.

Figure 8. Variation of Energy consumption with the air velocity for different configurations.

Table 4. Comparison of the present study with the available literature.

Sl. No	Author	System configuration	Operating parameters	Major results	Remarks
1	Present study	Combination of the indirect-direct evaporative cooler with coconut coir packing	Water flow rate = 3 LPM Air velocity =5 m/s	HE =0.64 ΔDBT = 7.6ºC	Observed a huge decrease in exit temperature without an appreciable increase in RH
2	Heidarinejad et al. (2009)	Two-stage evaporative cooling	Water flow rate = 1 LPM Airflow rate= 0.590 m^3/s	HE= 60% ER= 0.4 g/s	The proposed unit saved 60% of energy with the increase in the water consumption by 55%.
3	Al-Juwayhel et al. (2004)	One, two and three-stage (Direct, indirect and Mechanical vapour compression system)	Air velocity= 8 m/s	HE= 60% ER=0.12 g/s Maximum temperature drop of 25°C	Three-stage packing gave higher results compared with two and single-stage humidifiers.
4	Saleh and Al-Nimr (2008)	Multi-stage Evaporative cooling	Air temperature= 35° C RH= 60%	ER= 0.20 g/s ΔT= 20°C	Maximum temperature reduction of 20 °C in humid conditions, and the system was cost-effective.
5	Malli et al. (2011)	Varying thickness multi-stage evaporative cooling	Air velocity= 1.8–4 m/s Packing thickness= 75, 100 and 150 mm	HE= 80% ER= 2.33 g/s	Higher packing thickness increased humidification, and the air velocity increased the evaporation rate.
6	Mitz-Hernandez et al. (2022)	Regenerative dew point evaporative cooling	A numerical model was developed for a regenerative dew point evaporative cooling to simulate the varied properties of air including temperature, humidity ratio and pressure.	Maximum thermal performance of 90.9% was obtained during very arid conditions and a minimum of 62% for warm climate conditions.	The developed model with the variables that depend on the temperature, humidity ratio and atmospheric pressure fit experimental data with a high accuracy of around 93%.
7.	Min Y et al.(2022)	Condensation evolution of primary air in the indirect evaporative cooler was experimentally studied	Inlet air conditions were maintained at a temperature of 30°C, 80% RH and velocity of 1.8 m/s	During the test, the moisture difference between inlet and outlet primary air reached a peak of 6.0 g/kg and then decreased to 3.8 g/kg with the growth of condensation. Subsequently wet bulb effectiveness also decreased.	It was concluded that convective heat transfer in IEC can be increased by modifying the surface materials which helps to reduce the condensate mass retained on the plate surface.

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Data availability statement

Data will be made available on reasonable request.