Thermal Management and Energy Recovery in Commercial Dishwashers: A Theoretical and Experimental Study
Abstract
1. Introduction
2. Methodology and Technique
2.1. Theoretical Study
2.2. Experimental Study
3. Results and Discussion
4. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Nomenclature
Cd | discharge coefficient of the orifice (0.8) |
cp | heat capacity of water (Kj/kg °C) |
dH | hydrodynamic diameter of the tube (m) |
di | inside tube diameter (m) |
do | outside battery diameter (m) |
Ef | fraction of sprayed water that reaches the battery surface (25%) |
f | friction factor |
hD | convective heat transfer coefficient for droplets (W/m2°C) |
hL | total head loss (m) |
k | loss coefficient for the 90° turns (0.3) |
Kw | thermal conductivity of sprayed water (W/m°C) |
L | length of the battery (m) |
Lw | tube length that water flows through to reach the wash arms (m) |
ṁs | flow rate of sprayed water (kg/s) |
n | number of orifices on each arm (8) |
SR | saving ratio |
Tin,freshwater | temperature of cold inlet water (°C) |
Tout,battery | water temperature inside the battery as well as the sprayed water temperature leaving the battery surface (°C) |
Tout,boiler | temperature of water leaving the boiler (°C) |
∆Tw/ retro. | temperature difference with retrofit (30 °C) |
∆Tw/o retro. | temperature difference without retrofit (60 °C) |
twash | duration of the wash cycle (60 s) |
Twash, sprayed | temperature of the sprayed water (62 ± 2 °C) |
u | velocity of the fluid in the tube (m/s) |
uo | velocity of the jet (m/s) |
WR | wetting ratio (~20–30%) |
x | fraction related to head loss in the top arm |
1 − x | fraction related to head loss in the bottom arm |
β | ratio of orifice diameter to the tube diameter |
ϵ | average pipe roughness (m) |
μ | viscosity of sprayed water (Pa.s) |
ν | kinematic viscosity of sprayed water (m2/s) |
ρ | water density (kg/m3) |
σ | surface tension of sprayed water (N/m) |
References
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Scenarios | Start-up (min) | CYCLE-I | CYCLE-II | CYCLE-III | CYCLE-IV | CYCLE-V | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Waiting time (min) | Loading (min) | Rinse/Wash (min) | Waiting time (min) | Loading (min) | Rinse/Wash (min) | Waiting time (min) | Loading (min) | Rinse/Wash (min) | Waiting time (min) | Loading (min) | Rinse/Wash (min) | Waiting time (min) | Loading (min) | Rinse/Wash (min) | ||
Scenario 1 | 60 | 180 | 0 | Default | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
Scenario 2 | 60 | 120 | 1 | Default | 120 | 1 | Default | 120 | 1 | Default | NA | NA | NA | NA | NA | NA |
Scenario 3 | 60 | 60 | 1 | Default | 60 | 1 | Default | 60 | 1 | Default | 60 | 1 | Default | NA | NA | NA |
Scenario 4 | 60 | 30 | 1 | Default | 30 | 1 | Default | 30 | 1 | Default | 30 | 1 | Default | NA | NA | NA |
Scenario 5 | 60 | 15 | 1 | Default | 15 | 1 | Default | 15 | 1 | Default | 15 | 1 | Default | 15 | 1 | Default |
Scenario 6 | 60 | 5 | 1 | Default | 5 | 1 | Default | 5 | 1 | Default | 5 | 1 | Default | 5 | 1 | Default |
Scenario 7 | 60 | 0 | 1 | Default | 0 | 1 | Default | 0 | 1 | Default | 0 | 1 | Default | 0 | 1 | Default |
WR | Tout, battery °C (Equation (11)) | Tout, battery °C (Equation (12)) |
---|---|---|
20 | 56.05 | 58.8 |
25 | 58.2 | 60.2 |
30 | 59.6 | 61 |
Parameter | Value/Equation | Description |
---|---|---|
x | 0.49 | fraction of sprayed water flowing in the top arm |
hL (m) | 6.1 | total head loss |
ṁs (kg/s) | 1 | mass flow rate of sprayed wash water |
L (m) | 33.8Ef | relationship between L and Ef (Equation (3)) |
Scenarios | Total Energy Savings | Average Energy Savings per Wash Cycle | Cost Savings per Cycle ($) |
---|---|---|---|
1 | 37% | 0 | 0 |
2 | 38% | 53% | 0.14 |
3 | 41% | 46% | 0.12 |
4 | 44% | 41% | 0.10 |
5 | 49% | 49% | 0.17 |
6 | 48% | 46% | 0.15 |
7 | - | - |
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Zanganeh, J.; Seyfaee, A.; Gates, G.; Moghtaderi, B. Thermal Management and Energy Recovery in Commercial Dishwashers: A Theoretical and Experimental Study. Energies 2025, 18, 2338. https://doi.org/10.3390/en18092338
Zanganeh J, Seyfaee A, Gates G, Moghtaderi B. Thermal Management and Energy Recovery in Commercial Dishwashers: A Theoretical and Experimental Study. Energies. 2025; 18(9):2338. https://doi.org/10.3390/en18092338
Chicago/Turabian StyleZanganeh, Jafar, Adrian Seyfaee, Greg Gates, and Behdad Moghtaderi. 2025. "Thermal Management and Energy Recovery in Commercial Dishwashers: A Theoretical and Experimental Study" Energies 18, no. 9: 2338. https://doi.org/10.3390/en18092338
APA StyleZanganeh, J., Seyfaee, A., Gates, G., & Moghtaderi, B. (2025). Thermal Management and Energy Recovery in Commercial Dishwashers: A Theoretical and Experimental Study. Energies, 18(9), 2338. https://doi.org/10.3390/en18092338