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Feasibility of Components

Feasibility of Components. Clara Echavarria & Jonathon Locke. Efficiency Estimation Functional Diagram: Part 1 Cooling Load Required. Inputs/Givens Volume of Ice (3.5 gal) Density of Ice (736 kg/m 3 ) Latent Heat of Ice, h sf (333.6 KJ/kg)

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Feasibility of Components

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  1. Feasibility of Components Clara Echavarria & Jonathon Locke

  2. Efficiency Estimation Functional Diagram: Part 1 Cooling Load Required Inputs/Givens Volume of Ice (3.5 gal) Density of Ice (736 kg/m3) Latent Heat of Ice, hsf (333.6 KJ/kg) Melt time of 1 hour (3600 s) Governing Equations Output Cooling Load (900 W) Constraints and Assumptions Steady State Ice can be melted in 1 hour

  3. Efficiency Estimation Functional Diagram: Part 2 Fan/Pump sizing Constraints and Assumptions Ideal gas Incompressible flow Constant Pressure (Cp) Uniform Flow Steady State Ambient air Temp of 22⁰C and output temp of 13⁰C Water temp of 0⁰C from ice box Ice can be melted in 1 hour Governing Equations Output Air Flow Rate (255 CFM) Coolant Flow Rate (1 GPM -> at least 0.5) Inputs/Givens Heat Flux (900W) Fluid properties of air and water

  4. Efficiency Estimation Functional Diagram: Part 3 COP calculation Constraints and Assumptions No pumping losses 65% pump efficiency (low) Fan at 100% power Steady State 2x calculated pump power to accommodate losses z (H) of water in pumping loop equal to 1m (would be less in actual unit) Governing Equations Output COP = 10 Input data Cooling Load (900 watts) Coolant Flow rate (1 GPM -> at least 0.5 GPM) Fan power (40W) Constants Density of Water (1000 kg/m3)

  5. Preliminary testing

  6. Heat Exchanger selection • Size: 12”X12” • 99.9% pure copper • 3/8” seamless tubing, 3 core construction • High flow of 12 GPM, 175 psi and can handle up to 350F • Aluminum fins are 12 per inch, 22 gauge galvanized steel frame • The design enables heating loads of 50,000-60,000 BTU per square foot

  7. Heat Exchanger Feasibility Calculations: Part 1 Governing Equations Constants and givens (from vendor) CFM air, GPM water, rating (q) Inlet temperatures (used to figure out the densities of the fluids and the specific heat capacities) Output UA value at different flow rates of air and water • Constraints and Assumptions • - Ideal gas • Incompressible flow • Constant Pressure (Cp) • Uniform Flow

  8. Data Analysis • The value of UA depends on the flow conditions and fluid properties. • Assume an empirical relationship between UA and mass flow rates using the results previously obtained for UA. • Assuming a polynomial equation of the form: • Use Excel’s solver to find the coefficients A, B, C, D, E, F.

  9. Pump and fan selection is driven by the selected heat exchanger. • The air and water flow rates used need to be in the ranges of the heat exchanger testing data in order to minimize deviation of the analytical calculations.

  10. Fan selection • The heat exchanger model fits best between 600 CFM and 1000 CFM. • DC fans that can handle this flow at the required pressure drops are easier to find than AC fans that can do the same. • AC fans are more expensive, but DC fans require a car battery or a power converter.

  11. Fan Selection: AC Axial Fan ΔP (w.c.) Both the radiator pressure drop versus flow and the fan pressure capabilities versus flow were plotted together to show the optimum flow point. The point where the two curves intersect is at 645 CFM and 0.41” of water. Based on the Flow Selection Analysis: Static Pressure of System : 0.41” water Air Flow @ S.P. : 645 CFM Voltage: 115 VAC Power: 160 W

  12. Pump Selection: system losses considered • Radiator pressure drop • 7 Sharp radius PVC elbows • Straight piping length • Entrance loss • Sudden contraction (after pump) • Tee loss • Gate valve loss • Δ Height of the system

  13. Important Equations Where H = head loss f = friction factor L = length/equivalent length v = velocity D = pipe diameter g = gravitational constant K = loss coefficient Friction loss formulas Equivalent length method Loss coefficient method

  14. System Properties and Results As seen above, the system losses are minimal.

  15. Pump Selected Dimensions: Tiny Might Spa Pump • Properties: • 1/16 HP • 115 volt, 0.8 amps • 92 Watts • Capable of 0-20 GPM • Capable for 0-23.1 ft of Head

  16. Pump Head vs. Flow Curve Feet of head Flow (GPM) This pump is easily capable of the required head at Q=5 GPM. A valve will be used to control the flow. This is the cheapest, smallest, and lowest power pump available that will meet system requirements. The flow capability of the pump provides flexibility for testing and data collection.

  17. Heat Exchanger Feasibility Calculations: Part 2 Governing Equations Constants and givens Flows from fan and pump (645 CFM, 5 GPM) Inlet temperatures Output Heat exchanger cooling load • Constraints and Assumptions • - Ideal gas • Incompressible flow • Constant Pressure • Uniform Flow

  18. Run Time Constants and givens Latent Heat of Ice, hsf (333.6 KJ/kg) Volume of ice (16 gal) Density of Ice (736 kg/m3) Cooling load of heat exchanger(4715.1 W) Governing Equations Output Time required to melt the ice in the tank = 52.6 min Constraints and AssumptionsSteady-State

  19. Final Efficiency Functional Diagram (Final Testing) Measured data Tof water in and out of radiator Win from “plug power meter” Water flow rate Output air temperature Air speed Governing Equations Output Final/Overall COP of unit Constants and givens Area (A)of air flow Fluid properties of air (density, Cp) Ambient air temperature • Constraints and Assumptions • Ideal gas • Incompressible flow • Constant Pressure (Cp) • Uniform Flow

  20. Insulation Pipe Insulation Box Insulation

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