FEASIBILITY OF COMPONENTS CLARA ECHAVARRIA & JONATHON LOCKE

Efficiency Estimation Functional Diagram: Part 1 Cooling Load Required Inputs/Givens 1.Volume of Ice (3.5 gal) 2.Density of Ice (736 kg/m 3 ) 3.Latent Heat of Ice, h sf (333.6 KJ/kg) 4.Melt time of 1 hour (3600 s) Constraints and Assumptions 1.Steady State 2.Ice can be melted in 1 hour Output 1. Cooling Load (900 W)

Efficiency Estimation Functional Diagram: Part 2 Fan/Pump sizing Inputs/Givens 1.Heat Flux (900W) 2.Fluid properties of air and water Constraints and Assumptions 1.Ideal gas 2.Incompressible flow 3.Constant Pressure (Cp) 4.Uniform Flow 5.Steady State 6.Ambient air Temp of 22⁰C and output temp of 13⁰C 7.Water temp of 0⁰C from ice box 8.Ice can be melted in 1 hour Output 1. Air Flow Rate (255 CFM) 2.Coolant Flow Rate (1 GPM -> at least 0.5)

Input data 1.Cooling Load (900 watts) 2.Coolant Flow rate (1 GPM -> at least 0.5 GPM) 3.Fan power (40W) Constants Density of Water (1000 kg/m 3 ) Constraints and Assumptions 1.No pumping losses 2.65% pump efficiency (low) 3.Fan at 100% power 4.Steady State 5.2x calculated pump power to accommodate losses 6.  z (H) of water in pumping loop equal to 1m (would be less in actual unit) Output COP = 10 Efficiency Estimation Functional Diagram: Part 3 COP calculation

Preliminary testing

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 12X12 CFM APD (w.c.)0.35LAT0.58LAT0.85LATWPD (ft. w.) GPM5BTU

Constants and givens (from vendor) 1.CFM air, GPM water, rating (q) 2.Inlet temperatures (used to figure out the densities of the fluids and the specific heat capacities) Constraints and Assumptions - Ideal gas - Incompressible flow - Constant Pressure (Cp) - Uniform Flow Output UA value at different flow rates of air and water Heat Exchanger Feasibility Calculations: Part 1

Data Analysis

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. 12”X12” CFM APD (w.c.)0.35LAT0.58LAT0.85LATWPD (ft. w.) GPM5BTU

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.

Fan Selection: AC Axial Fan 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 S.P. : 645 CFM Voltage: 115 VAC Power: 160 W ΔP (w.c.)

GPMCOP Cooling load (W) Run time (min) Air outlet temperature (⁰F)

Pump Selection: system losses considered 1.Radiator pressure drop 2.7 Sharp radius PVC elbows 3.Straight piping length 4.Entrance loss 5.Sudden contraction (after pump) 6.Tee loss 7.Gate valve loss 8.Δ Height of the system

Important Equations Where H = head loss f = friction factor L = length/equivalent length v = velocity D = pipe diameter g = gravitational constant K = loss coefficient

System Properties and Results As seen above, the system losses are minimal. Flow5gpm m 3 /s PVC1in m Area m2m2 Velocity m/s Relative roughness m e/d µ kg/(m*s) Re Friction factor Radiator losses0.3079m Elbow losses0.0227m Pipe losses0.0377m Entrance losses0.0198m S.C. losses0.0781m Tee losses0.001m Gate valve losses0.0004m Δ Height m Total losses1.1534m 3.784ft

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

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. Pump Head vs. Flow Curve Feet of head Flow (GPM)

Constraints and Assumptions - Ideal gas - Incompressible flow - Constant Pressure -Uniform Flow Heat Exchanger Feasibility Calculations: Part 2

Constants and givens 1.Latent Heat of Ice, h sf (333.6 KJ/kg) 2.Volume of ice (16 gal) 3.Density of Ice (736 kg/m 3 ) 4.Cooling load of heat exchanger( W) Constraints and Assumptions Steady-State Output Time required to melt the ice in the tank = 52.6 min Run Time

Measured data 1.  T of water in and out of radiator 2.W in from “plug power meter” 3.Water flow rate 4.Output air temperature 5.Air speed Constants and givens 1.Area (A) of air flow 2.Fluid properties of air (density, Cp) 3.Ambient air temperature Constraints and Assumptions Ideal gas Incompressible flow Constant Pressure (Cp) Uniform Flow Output Final/Overall COP of unit Final Efficiency Functional Diagram (Final Testing)

Insulation Box Insulation Pipe Insulation R Value5.78h*ft 2 * o F/Btu Foam Ins m 2 *K/W Int. Temp0⁰C⁰C External Temp30⁰C⁰C Delta T30⁰C⁰C Delta T30K Front/Back572in 2 Sides360in 2 Top/Bottom440in 2 Total Area1372in 2 Total Area9.5ft 2 Total Area0.885m2m2 Heat Loss Q26.1W Heat Loss Q89.0BTU/hr System Heat Transfer W % of System0.60 This is an acceptable percentage. Note that the air and metal/plexiglass will add additional resistance (although minimal) Insulation Information 1.5" Insulfoam 1-1/2-in x 2-ft x 4-ft Expanded Polystyrene Insulated Sheathing 8ft 2 for $4.42 R Value3.33(h*ft 2 * o F/Btu)/inch Inches in Foam Ins m 2 *K/W Int. Temp C External Temp30 C Delta T30 K Total Area ft 2 Heat Loss Q W Heat Loss Q BTU/hr System Heat Transfer W % of System %