Module Code(s) MEC09722, Module Title: Energy System Design

Coursework – Ground Source Heat Pump - Ground Loop Design and Performance Analysis

Assessment regulations and academic integrity

The University rules on Academic Integrity apply to all submissions. The student academic integrity regulationscontain a detailed definition of academic integrity

breaches.

•   You cannot knowingly permit another student to copy all or part of your work.

•   You must not share your work with other students. This includes posting any of your work in any repository that is accessible to others (such as GitHub) and applies also after you have completed the course.

•   Asking coursework-related questions in external online forums (such as Stackoverflow) is NOT permitted.

By submitting the report, you are confirming that:

•    It is your own work except where explicit reference is made to the contribution of others.

•    It has not been submitted for any module, programme or degree at Edinburgh Napier University or any other institution.

•    If you have made use of generative Artificial Intelligence (AI) tools, you have done so only as allowed for this assessment, and have provided the relevant details in the coursework declaration.

1.0    Academic Regulations

(a)      Academic skills support: In advance of submission, you can access the support of the academic skills team. They can help you with any aspect of the assessment that you might struggle with, that is not content related. For example, they can help with time-management, effective reading and note-making, and any aspect of academic writing that you might struggle with. This support is provided through workshops and individual appointments which are bookable online via MyNapier:

Improve your Academic & Study Skills (napier.ac.uk). You can also directly email the Academic Skills Adviser, Hannah Awcock, h.awcock@napier.ac.uk for any specific academic skills support you require.

(b) Use of generative AI: [If not covered elsewhere, eg a Moodle Quiz]. Please include the following declaration on the first page of your submitted coursework:

2.0    COURSEWORK SPECIFICATION

Ground Source Heat Pump - Ground Loop Design and Performance Analysis:

Considering yourself as a thermal engineering consultant, you have been approached by a prospective client asking for a feasibility study on the potential for installing a ground source heat pump to heat a property in Southern Scotland. The house is a modern eco-home, and the client has some knowledge of the site and background information on likely costs and is keen to see if it is worthwhile proceeding with the project.

The house is a single story storey structure, 15m long and 12m wide, The floor to ceiling height is 3m. The house has 6 large windows (1.2x1.5m) facing south, 4 east/west (1.2x1m) and 2 facing north (same size as E/W, but no significant solar gains at this location). the building is typically occupied by 4 people with 5kWh/day/person of casual gains via cooking, TV, PC and other related activities. Also assume 6 lights on at any one time and 75 watts of casual gains per person. The effective ventilation rate is 8m3/hr/m2 .

The U values are as follows: Ufloor  = 0.25 W/m2K, Windows are double glazed 1.7 W/m2K, two doors UDoor  (1.5m2 each) = 0.6 W/m2K, URoof  = 0.24 W/m2K. The walls consist of 300mm of solid brick (1.125 w/mK), with an external coating of lime render 25mm thick (0.5 W/mK). Inside of the brick there is an airgap of 10mm (0.23 W/mK conductivity) onto which 100mm of sheep’s wool insulation (k = 0.035 W/mK) has been placed, which is then sealed by 20mm of plasterboard (k = 0.16 W/mK) on the inside.    The degree days per month and the solar gain factors are given below (northerly solar  gains are considered to be negligible), as well as the solar availability to the ground area under which the GSHP will be placed:

Note Qgain for solar = SGf x days of the month x area = kWh/month

Based on the data above you should able to make an estimate for the monthly heat requirements and thus estimate the heat input required per month for the house. Note that the above values only covering heating. Hot water demand will be approximately  2kWh’s per person per day.

It is planned to locate the GSHP under the front garden of the house, with soil details as below:

Dimensions:  = 14 m long x 14 m wide

Soil type: clay, properties:

k =0.9 W/m.K ρ = 1620 kg/m3 , Cp=1.25 kJ/kg.K

From previous installations experience, you are considering using a vertical slinky of radius 1m, with 1m overlap, in trenches spaced 2 m apart, with the top of the coil 1m below ground level. The initial pipe for consideration is polypropylene, with a manufacturer’s specified thermal conductivity of 0.45 W/m.K. The internal surface roughness is 3 x 10-6  m, and the internal diameter and wall thickness are, respectively, 28 mm and 2 mm.

Considering, and clearly specifying, an appropriate fluid inlet temperature and glycol concentration, define all necessary thermophysical properties to allow a detailed analysis of the potential rate of heat absorption from the site. You may consider the application of either a 150 W, a 200 W or 250 W circulating pump (electrical rating), each with an efficiency of 83%. {Note: You may wish to start your analysis by considering a volumetric flow rate between 0.5 l/s and 0.65 l/s to determine head loss, and hydraulic output, and thence use an iterative procedure to determine a realistic flow rate that can be achieved by your chosen pump}.

Considering the rate of heat absorption for the pipe in 20 m incremental steps, determine the total rate of heat absorption that can be achieved for the site, and the fluid temperature at outlet. You may wish to consider the effect of alternative pipe dimensions on thermal performance. Clearly specify your assumed system CoP, determine the maximum rate of heat delivery to the property, and critically appraise the suitability of the system to meet the heating requirements detailed above. You may also wish to consider a “coldest day scenario” in your analysis, and the effect of heat removal on ground temperature, and hence system operational performance.

Another consideration are the economics and carbon footprint of the setup. What sort of cost benefit would such as system provide and would significantly cut back on carbon emissions. In the event of any shortfall in performance. You also might want to consider what sort of subsidies are available to support the installation of a heat pump and would this house qualify.

Another issue you might also wish to address the issue of a possible backup or supplementary heating system (or possibly modifications to the house to lower the heat demand to match supply). The homeowner is also interested in generating renewable energy on his property, which could help power the heat pump, as well as provide electricity to the home. Its worth noting that this house is off the gas grid.

Your report should include an executive summary detailing the salient points from your analysis. You should state clearly, and justify, all assumptions made. You should provide clear argument for your chosen pump, and consider both the limitations and benefits of using this type of heating system. Detailed calculations may be presented in an appendix, or in an attached spreadsheet, but should not be within the main body of text.

Based on the discussion chapter you should finish with a conclusion, which should summarise the findings of your report. It is crucial that your report is well supported by references. Ideally these should be drawn from peer reviewed academic journals as much as possible. However, given the practical nature of the report government reports, manufacturers data sheets, textbooks and course notes are acceptable alternatives.

3.0    RESOURCES

Spreadsheets on moodle, including EthGlyc-data.xls

The resources required for this assessment are contained within the taught material issued in class, namely the handouts, associated examples and tutorial work.

Additional resources will be available in text books, the internet and in particular scientific journal papers. These are best sourced using sites such as www.sciencedirect.comor “ Google Scholar” Note that you will need to be using a university based PC account to access journal papers, as many are behind a pay-wall.

4.0    REPORT FORMAT AND ASSESSMENT CRITERIA

Your report should be written following the Report Writing Guidelines that should be available in your Programme Area of Moodle and also in your Programme Handbook. Ensure that your report is written in the 3rd  person and using the past tense.

Your report will be assessed on its clarity and its technical accuracy. Standard reporting features such as an Abstract, an Introduction and Conclusion/Summary should be incorporated.

•  Guide length for the report is 2000 words.

•  Title page, list of contents, abstract, headings, appendices, and references are not included in the word count.

•  Marks will be given for evidence of research and the application of this via your calculations.

•  It is important to fine tune calculations and provide justifications for any assump- tions made as well as any design decisions you make.

•  Marks will be given for the quality and depth of discussion and critical analysis.

•  You must write material which is your own. If referring to other material, you are required to provide references. If there is a lot of material from other sources; pré-   cis, or summarise it in your own words, add your own thoughts and observations. It is not acceptable to copy large pieces of information from other sources, even if   it is referenced. Any material in the report that is clearly a verbatim copy from  a reference source, or that has been generated by a chatbot, will be dis-counted. The examiners reserve the right to request a viva to verify students knowledge of the subject.

•  All research sources should be listed clearly. Where possible, references should be from quality peer reviewed sources (Journal Articles, Books, etc.)

•  The Harvard referencing conventions is recommended for acknowledging sources of material. Guidelines for the School of Engineering & the Built Environment are available via the SEBE Referencing Guidelines.

5.0    LEARNING OUTCOMES COVERED

LO2     Define energy system boundaries

LO3     Select appropriate pumps and fans for specific applications

LO4    Analyse simple heat transfer system

LO5     Design simple energy system (specify main components for a heat pump system)