1. Solar Water Heating on StFX Campus
Final Presentation
Meghan Hanington, Alexander MacDonald,
Blake Meech, Connor Hanna & Alex MacDonald

2. Outline Background Information Domestic hot water & Current Process
Solar Water Heating
Design Description
System overview & Requirements
Components & Drawings
Analysis
Structural Analysis & System performance
Cost Analysis
System limitations

3. Domestic Hot Water
Domestic hot water is hot water that is used within a building for showering, cooking or cleaning
A typical system takes water from a central water supply and uses electricity or burns a fossil fuel to generate heat in a boiler
Heat is transferred to the water supply and the water temperature rises
Trim?

4. Problem
On StFX campus, domestic hot water is heated using steam that is generated in the Central Heating Plant using Bunker B fuel and fish oil.
Overall efficiency around 69%
Burning bunker fuel produces greenhouse gases and may not be sustainable
Fuel must be shipped from Quebec 3 times per week which further increases the associated costs and carbon emissions
Source: [1]

5. Project Site MacIsaac Hall
Building has large south-facing flat and sloped roof sections suitable for solar water heating
Buildings mechanical room and washrooms are located directly under the flat roof section
Estimated daily hot water demand of
17550 L

6. Project Goals
Determine the available MacIsaac Hall roof area and increased load on the roof from the solar collectors
Identify the methods for integrating the solar water to the existing steam system to properly preheat water
Determine the proper equipment necessary in order to ensure the SWH system works correctly and safely
Analyze the performance of the SWH system and provide estimates on energy output
Conduct a cost and environmental analysis on the project to determine its feasibility and benefits

7. What is Solar Water Heating?
Solar water heating involves converting energy from the sun into heat for water heating.
Wide variety of system types
Direct and indirect
Active and passive
Source: [2]

8. Direct or Indirect? Active or Passive?
Closed loop piping
Heat transfer fluid transfers heat absorbed in the solar collectors to the domestic water supply
Direct
Directly heat water
Prone to freezing in cold climates
Active
Pumps and controllers circulate the working fluid from collectors to the storage tank
Passive
No pumps
Less control over flow of fluid
MacIsaac Hall site will be indirect and active
Full control over fluid and protection from freezing
Trim?

9. System Overview
Flowchart

10. Design Requirements
Produce energy for all months of occupancy in MacIsaac Hall
100% powered by renewable energy
Have a fail-safe control system to protect the glycol fluid and optimize energy production.
Integrate with the current steam based hot water generation system
Provide energy storage to ensure energy is not wasted during peak production.

11. Required Equipment Solar collectors Solar pump PV solar panels
Temperature sensors and a solar controller
Glycol working fluid
Storage tank with a heat exchanger
Drain back tank
Piping
Wiring
Frame and mounting rods
Source: [2]

12. Location of Installation
On the flat and sloped roof sections directly above MacIsaac Hall’s mechanical room
System complexity can be reduced
Pipes can travel from the roof directly to the mechanical room through a nearby existing chimney chute that is currently not in use
The existing steam hot water heater is located in this mechanical room and there is available space for a storage and drain back tank
The available roof space was found using AutoCAD files for the building provided by Kevin Latimer
20 Thermo-Dynamics Ltd. G Series solar collectors could fit in this area

14. Location of Installation

18. G Series Solar Collectors
Produced by Thermo Dynamics Ltd.
Design life of 35 years
Flat plate type mounted on a lightweight aluminum frame
Can withstand very high operating temperatures and pressures
Can be arranged in an array of any size
Installed on flat roof at 37 degrees
Optimal angle depends on latitude [3]
Installed on sloped roof at 27 degrees

19. Shadow Calculation
Maximum shadow for the collectors mounted on the flat roof
Source [4]
Trim?

21. Collector Performance
Maximum ideal efficiency for the G Series solar collectors is [2]
Converting solar radiation to energy stored in the glycol solution
The angle of inclination, position in relation to the sun, geographical location and weather influence the solar collector efficiency
To estimate an actual efficiency for the panels, the software RETScreen was used and an efficiency of 0.55 was calculated.
In knowing the efficiency and daily averages for solar radiation we can calculate the potential energy output for the total array of solar collectors

22. Example Calculation
Energy production for a typical day in January

23. Solar Pump Powered by small, 20W solar panels
Connected to temperature sensors that will signal to turn the pump on or off.
For drain back systems, Thermo Dynamics recommends a system operating pressure below 30 psi ( Pa)
Can determine the proper capacity to meet the requirements for flow rate and pump head

24. Pump Calculations 3 parallel sets of collectors connected in series
Each set has maximum flow rate of 1.5 L/min for at total of 4.5 L/min
Required pump head can be calculated
The solar pumps available from Thermo Dynamics all produce up to 35m of head (different flow rate capacities)
If a design pressure of 20 psi ( Pa) is chosen, the required pump head becomes 32m
Direct-Drive Solar Pump (P118330) was selected
Can easily handle the flow rate requirement of 4.5 L/min

25. Pump Calculations Cont.

26. Control System
Involves the solar pump, temperature sensors and a drain back tank
Three temperature sensors should be used
Solar pump is only activated by the controller when the return line is at a higher temperature than the supply line
Controller also has low and high temperature range for the sensors
High limit should be set at 90 C and the low limit at -10 C
Pump shuts off, glycol flows to drain back tank via gravity

27. PV Solar Panels The solar pump operates using a 12 volt (DC) supply
Power requirement is 35W
Two 20W PV modules can be used
The approximate length of cable is 20m, connecting the solar controller in the mechanical room to the PV panels on the roof
#14 American Wire Gage (AWG) cable is recommended by the manufacturer
Has an ampacity rating (maximum current) of 15 Amps [5], so operating at 1.67 Amps is safe

28. Calculation
To supply 20W of power at 12 volts, the current requirement will be 1.67 Amps

29. Piping and Wiring Piping 3/4’’ unions for tanks and solar collectors
3/4’’ copper pipe is sold by 50’ lengths
Insulation is sold per 6’
Total length estimate is 131m
Wiring
PV and sensor wire is #14 AWG
Sold per 1’
Total length estimate of 25m

30. Heat Transfer Fluid
Propylene Glycol is a chemical commonly used in heat transfer applications
Has a wide operating temperature range
Used as heat transfer fluid due to its lower freezing temperature
Allows the solution to be safe for use in the winter
Thermo-Dynamics Ltd. offers two propylene glycol fluids

31. Advantages to Mixed Glycol Solution
The mixed glycol solution has:
Cheaper cost
Higher specific heat capacity
Increased heat transfer capabilities
Downside is the higher freezing temperature
Antigonish does not regularly reach -24 °C
Control system will ensure fluid is protected regardless

32. Drain Back Tank
Protect the system by ensuring that the glycol does not
begin to freeze or boil
Controlled by the solar pump
HTP Drain Back Tank
The maximum volume of glycol that could be in our system is 83L
HTP Drain Back Tank SSU-20DB
Capacity
113L (30 Gallon)
Diameter
489mm (19.25 '')
Height
990mm (39'')
Inlet/Outlet connections
19.05 mm (3/4’’)
Cost
$905

33. Hot Water Storage Tank
Flexibility in choosing the size and number of hot water storage tanks
Hot water demand much greater than production rate
An indirect water heater was chosen (closed loop)
The glycol solution will be passing through the coil to transfer energy to the water
Bradford White Indirect Water Heater (269 L Capacity)
Very efficient
Minimal stand by heat losses of 1.1C per hour
Single Unit, $1500
Hot water stored at max of 71C

34. Storage Tank Cont Energy capacity Energy demand > Energy production
Water stored at 71°C (160°F)
Energy demand > Energy production
Even if there is no demand, the tank can store energy for 100 minutes of peak production from the collectors

35. Structural Analysis
Statically indeterminate axially loaded member (inclined solar collector)
Compatibility equation is to be used for this calculation
Determine if the Aluminum 6061-T6 supports at B & C will hold the collectors
Given the cross sectional area of the supports from Thermo Dynamics Ltd. manufacturer (square 0.041m x 0.041m)

36. Structural Analysis Cont
Found support reactions from equations (2)-(7)
From equation (1)
With max winds of 250 km/h winds, the wind force acting on the collector would be, P=8600N Source [6]
Max weight of solar collector with glycol fluid, W=450N
Solved for critical yield strength in supports from equation (8)

37. Structural Analysis Cont
Flat roof section
Sloped roof section

38. System Performance & Savings
Energy production limited by:
Collector and heat exchanger efficiency
Heat losses in pipes and storage tank

39. Cost Analysis
Cost breakdown
Could not obtain an installation quote

40. Cost Analysis Cont. Two potential project payback periods
Just including production in months of occupancy (September to May)
Savings of $2000 annually
17 year payback period
For full production all year
Savings of $3400 annually
10 year payback period

41. Environmental Analysis
System has potential to reduce C02 emissions by 7700 per year by reducing fuel consumption in Central Heating Plant
Equivalent to planting 350 trees [7]

42. Limitations
Proposed SWH system will only produce approximately 13% of the total hot water required in MacIsaac Hall during school months
Highest energy production occurs when building is empty

43. Conclusions Proposed SWH system has potential to:
Generate L of hot water in months of occupancy
Reduce fuel costs by $2000 annually
reduce C02 emissions by 7700 kg per year
Be powered 100% by renewable energy
Project payback period of 17 years
Reduced to 10 years if full year production is met

44. Recommendations Financing options to reduce project payback period
Incentives or grants
Look for ways to use energy produced in the summer in other buildings on campus
Hot water in other buildings, such as O’Regan & Riley Hall
Long term energy storage
Possible Geothermal applications
To completely replace steam hot water heating in MacIsaac Hall:
A larger number of collectors and storage tanks would be required

45. Project Schedule

46. Acknowledgements
Mr. Kevin Latimer StFX University Facilities Management
Dr. Emeka Oguejiofor, FEC, P.Eng. StFX University
Mr. Mohammad Azad StFX University
Mr. Paul Doiron, P.Eng. A.H. Roy & Associates
Mr. Daniel Doiron, P.Eng. A.H. Roy & Associates
Mr. Josh Bouchie, P.Eng. A.H. Roy & Associates
Mr. Ronald Kell, P.Eng. A.H. Roy & Associates

47. References Kevin Latimer, FM http://www.thermo-dynamics.com
2015 Canadian Electrical Code

48. Questions?