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Proposal for a Domestic Hot Water System. Researched by David Luong, Mark Piper, Colton Bangs, Aloysius Obodoako, Disha Katharani. Advantages of a Solar DHW System. Off-grid capability Ideal for isolated areas where connection to grid power is difficult to impossible Renewable energy source
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Proposal for a Domestic Hot Water System Researched by David Luong, Mark Piper, Colton Bangs, Aloysius Obodoako, Disha Katharani
Advantages of a Solar DHW System • Off-grid capability • Ideal for isolated areas where connection to grid power is difficult to impossible • Renewable energy source • System completely powered by solar radiation • Savings in long term investment
System Requirements • Family Size of 3-4 needing 80 gallons of hot water per day • Maximum storage tank temperature of 120 degrees F • Average of .63 kW-hrs per day • Assume 9 hours at 70 W peak in operation
Location Resources • For Philadelphia region, • Air temperature varies between 40-80 degrees Fahrenheit [4-27 degrees C] • Freezing conditions necessitate antifreeze in thermal circulation system (Propylene glycol typically used)
Solar Availability in Philadelphia Region K-T model of collector facing true south and ignoring local shading. Ground reflectivity is .2 for all months except .5 for January, .7 for February, and .4 for March.
System Overview PV Collectors Thermal Collector Controller Hot Water Out Storage Tank (with heat exchanger) Cold Water In Pump Schematic of DWH System
Decoding the Rating • Energy per day is given in the lower table as dependent on weather and temperature differential (Tin – Tamb) • The SRCC rates Philadelphia as about 14 MJ/m^2/day. • A typical clear day is said to receive 23 MJ/m^2/day, mildly cloudy is 17 MJ/m^2/day and cloudy is 11 MJ/m^2/day. • Thus, to analyze collector performance in Philadelphia, we used an average of the mildly cloudy and cloudy day ratings.
Collector Type The SRCC defines category C as a DHW in a warm climate, and category D as a DHW in a cool climate. We used category C to approximate the losses during summer and D in the winter.
Efficiency Rating Per Collector Area For our climate and purpose, the Mazdon TMA-600-30 panel manufactured by Thermo Technologies in Maryland is the most efficient.
Project Load Obviously, the winter load will determine the number of panels needed to achieve a desired level of DHW. The family will probably desire three of the Mazdon collectors in order to generate the majority of the winter DHW load needed.
Solar Thermal Collector • Fireball 2001 Solar Collector • Available in exciting architectural colors • Weights 38 lbs, easy installation • Copper Solar absorber plate • Coated with premium black crystal • Low emissivity and high absorptivity • Serpentine Design to increase fluid exposure to collector • Rigid Foam Installation for heat retention in the collector box • Coated with special heat reflecting white paint called Enerchron • Reflects heat back onto underside of the absorber • Lightweight Polycarbonate glazing • High insulation value and UV protection • Greenhouse effect
Solar Thermal Collector • Fireball 2001 Solar Collector from SolarRoofs.com • Critical Efficiency • 88% on Clear Day • 82% on Mildly Cloudy • 69% on Cloudy Day • Loss Coefficient (kW/m2/˚C • .0264 on Clear Day • .0233 on Mildly Cloudy • .0255 on Cloudy Day Features Heat Transfer Fluid can be potable water or Propylene glycol Maximum stagnation temperature of 250 degree F
Hot Water Storage Tank • ASHRAE recommends 20 gallons of hot water consumption per day per person • 120 gallon storage tanks in a 3 person household are typically used in the United States given its higher hot water consumption • Need to include heat exchanger to extract heat from glycol thermal fluid
Solar Storage TankRheem - Solaraide TC Features • 80 Gallon tank w/ heat exchanger • Tank Lining resist corrosion • Anode rod equalizes turbulent water action • Automatic temperature control • Collector feed located at front of tank • Has temp. and press. release valve
Solar Circulating Pump • Desire low power pump to transfer thermal energy from solar collector to storage tank through a heat transfer liquid. • Choose Propylene glycol to avoid freezing in system • Must operate in recommended flow rate range prescribed by solar thermal collector
El-SID Pump from Thermo Technologies • Highly conducive to PV panels because of its adjustable flow rate • Flow rate changes depending on sun brightness • Power Requirements and Performance • 12-17 VDC, Current range of .6-.85 Amps, Power of 10 watts • Maximum flow rate of 3.3 GPM • Optimal flow rate is 1.2 GPM for Mazdon Thermal Collector • Features • Long lasting • Absence of moving parts, brushes, or bearings • Magnetic coupled drive
Solar Controller • Needed to monitor system to avoid overheating the storage tank and to set efficient operating conditions • Ensures efficient heat collection • Desire low cost, low power consumption, and simple user-interface
Low Voltage Solar Energy Differential Controller • The USDT 2001 can be powered by a 24 volts DC or AC source to monitor supply and return temperatures. • Need to use two 12 volt PV panel in series to operate via VDC. • Microprocessor temperature controller to regular solar heating. LED to indicate supply temperature exceeding return temperature by programmable temperature difference. • Frost or cooling protection is regulated through return temperature monitoring. • Max. Adjustable deltaT of 50 F • BP protection range of 32-200 F • Anti-front cycling for system freeze protection (adjustable up to 50F) www.thermotechs.com
Photovoltaic Module • Needed to power solar circulation pump and controller. • Power requirements • 12 watts needed • Solar pump needs 12-17 VDC and controller needs 24 VDC
PV Panel from Solar Electric Supply-10 • 10 Watts,12V Nominal,17V Peak • Open Circuit Voltage: 21.6 V • Short Circuit Current: .7 A • Peak Voltage/Current: 17V/.59A • Polycrystalline Type • Frame • Anodized aluminum with tempered glass - Omni-mount frame • Need to have two placed in series to generate adequate voltage to power components
System Cost • Solar Thermal Collector $2500-3000 • PV Collector $89.95x2 • Storage Tank $1160 • Circulating Pump $229 • Solar Controller $159 • TOTAL ~$4500