P17484: Solar Water Heater
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Problem Definition

Table of Contents

Team Vision for Problem Definition Phase

The goal of the Problem Definition Phase of our project was to get a clear idea of what is required for our project, and to identify key requirements for our project.

Through talking with Rich Stein (RIT Controls Manager), we identified the Gene Polisseni Center (GPC) as having opportunity to use solar thermal technology to offset hot water costs. In the current state in the GPC, there are two 900 gallon hot water tanks and one 750 gallon holding tank. The hot water tanks remain steady at a temperature of 140F, where the holding tank hovers at about 70F. Demanded water is pulled from the hot water tanks, and that water is then replenished by the water in the 750 gallon holding tank. The temperature in the hot water tank is subsequently lowered, requiring the use of natural gas boilers to help raise the tank temperature back to 140F.

The use of a solar thermal water heating system can help to raise the temperature of the water that sits in the holding tank. The warmer the water that replenishes the hot water tanks, the less energy that will need to be spent to return the hot water tanks to 140F.

Our conversations with Rich also drove our Engineering Metrics and Customer Requirements which can both be seen in their respective sections below.

Project Summary

Harvesting the sun to heat water is not a new idea and has been done for centuries, but as technology expands, so does the ability to more effectively capture the sun’s energy and put it to use. Solar-thermal water heating systems capture the sun’s energy and use it to heat water to very high temperatures. RIT hopes to use this technology to aid in heating the domestic hot water storage tanks in the Gene Polisseni Center. The goal of this project is to complete a full scale feasibility study, proving that there is merit for installing a solar thermal system here at RIT. The goal is that a future system will provide the 750 gallon domestic hot water preheat tank with water as close as possible, but less than, 140F; and will achieve an ROI of < 5 years. The implementation of such a system may have many social and economic impacts and is important because:

A fully working model of the system will be required. Analysis will include: payback period, cost breakdown, feasibility/capacity measures, performance studies in different weather (rain/snow/clouds), as well as details on cost/BTU.

Click Here to View Problem Statement

Stakeholders

Use Cases

The use case identified below is the most common use case for the system we are proposing. It involves the typical situation where a person actuates a faucet in demand for hot water. While this is the case that is explained, this system has other pertinent use cases such as: if the boiler system were to break, the school could rely on the system (in a small capacity) to keep providing hot water as the main system is fixed. This use case involved the use of Evacuate Tube technology, though it is unclear whether or not this is the exact technology that will be used for the completion of this project.

Project Goals and Key Deliverables

The project goal is to implement solar-thermal water heaters on campus in current and future buildings.

Key deliverables for this project include a decision analysis to determine the best type of solar-thermal collector to fit RIT's needs, a feasibility study to determine if large scale solar-thermal water heating will be effective enough to supplement one of the buildings hot water loops, ROI estimation, and a working scale model of our desired system.

Customer Requirements (Needs)

Click here for the Customer Requirements live document.

Engineering Requirements (Metrics & Specifications)

Click here for the Engineering Requirements live document.

Risks

Technical Risks

  1. Cannot integrate system with the current RIT hot water loop.
  2. Cannot properly mount the system to a building roof.

Resource Risks

  1. Not adequate funding available to build a scale model of the desired system.
  2. Inadequate solar energy (sunlight) to heat water to the desired hot water loop temperatures.
  3. Lead times for receiving desired materials is long, thus causing delays in construction.
  4. Limited access to roof/building plans, cause our design to be less comprehensive and robust.

Safety Risks

  1. High potential for burns cause by hot water leaking from the system.
  2. Fall/drop hazard while working on building roofs.

Visit Planning & Execution for more details on Risk Management.

House of Quality

As seen above, the most important EM is "Collector Efficiency" which refers to the efficiency that will be seen by the specific solar thermal apparatus that the team chooses to purchase. This is followed closely by "Water Temperature" which has ramifications within our decision making as to which water loop the team will aim to supplement. These are followed then by "Size" which refers to the overall square footage of the system, and "System Efficiency" which relates the heat losses from the time the collector heats the water until the water is deposited into the campus loop.

Click here for the House of Quality live document.

Design Review Materials

Click here to view our Problem Definition Design Review Presentation.

Plans for next phase


Table of Contents

MSD I & II MSD I MSD II

Planning & Execution

Project Photos and Videos

Imagine RIT

Problem Definition

Systems Design

Preliminary Detailed Design

Detailed Design

Build & Test Prep

Subsystem Build & Test

Integrated System Build & Test

Integrated System Build & Test with Customer Demo

Customer Handoff & Final Project Documentation