MARL043 — Apply basic principles of marine engineering thermodynamics

1 Explain common thermodynamic principles

• 1.1Desired International System of Units (SI) applicable to thermodynamic calculations are developed
• 1.2Basic properties of fluids are outlined
• 1.3Gauge pressure is distinguished from absolute pressure
• 1.4Temperature is defined and temperature scales are outlined
• 1.5Calculations are performed by applying formulae for work, power and efficiency

2 Calculate properties of gas during expansion and compression

• 2.1Calculations are performed by applying Boyle’s, Charles’s and combined gas laws
• 2.2Gas equation is derived and applied to gas process calculations
• 2.3Specific heat of gases and the relationship between constant pressure (Cp), constant volume (Cv), gas constant (R) and Gamma (G) are defined
• 2.4Heat transfer is calculated for Cp and Cv processes
• 2.5Isothermal, adiabatic and polytropic processes are outlined and properties of gases after expansion and compression, including the effects of turbocharging, are calculated
• 2.6Work required to compress gases is illustrated and calculated

3 Explain methods of heat transfer

• 3.1Different forms of heat transfer and their application to marine systems are explained
• 3.2Heat transfer through flat layers is calculated
• 3.3Purpose of insulation is explained

4 Explain enthalpy and apply to mixture calculations

• 4.1Heat energy is defined
• 4.2Fundamental formula for heat energy transfer is developed
• 4.3Specific heat and its application are identified
• 4.4Enthalpy and change of phase are outlined
• 4.5Heat mixture problems involving water equivalent, ice, water and steam are solved
• 4.6Specific heat of materials are calculated
• 4.7Latent heat and dryness fraction are identified
• 4.8Steam tables are used to find values of enthalpy for water, saturated and superheated steam and dryness fraction
• 4.9Temperature/enthalpy diagram is constructed from steam table data

5 Explain steam plants and calculate thermal efficiency

• 5.1Basic steam plant cycles are sketched and function of each component is outlined
• 5.2Steam cycles on a temperature/enthalpy diagram are illustrated
• 5.3Effects of superheating and under-cooling are clarified
• 5.4Calculations are performed for heat supplied, rejected, work and thermal efficiency of a steam plant
• 5.5Methods of improving cycle efficiency are outlined

6 Explain operation of internal combustion engine cycles

• 6.1Operating principles of two-stroke and four-stroke internal combustion engines are outlined
• 6.2Differentiation is made, by use of a pressure/volume diagram, between Otto, diesel and dual combustion cycles
• 6.3Mean effective pressure is calculated from an indicator diagram
• 6.4Indicated power formula is developed and related calculations are solved
• 6.5Specific fuel consumption is defined and calculated
• 6.6Ideal cycle and air standard efficiency is defined

7 Explain operating cycle of reciprocating air compressors

• 7.1Pressure/volume diagram is used to describe operating cycle of single stage reciprocating air compressors
• 7.2Mass of air delivered by single stage reciprocating air compressors is calculated
• 7.3Clearance volume and its effect on volumetric efficiency is outlined, and volumetric efficiency is calculated
• 7.4Work per cycle for isothermal and polytropic processes is calculated

8 Explain operating cycle of RAC plant

• 8.1Principle of refrigeration is outlined
• 8.2Temperature/enthalpy and pressure/enthalpy diagrams are compared
• 8.3Refrigerants used in RAC machines are identified
• 8.4Refrigeration effect and plant capacity are defined
• 8.5Refrigeration tables are used to calculate refrigeration effect and condition of vapour after expansion
• 8.6Operating cycle of self-contained and centralised air conditioning systems are outlined and compared
• 8.7Relative humidity is defined and key features of a psychrometric chart are outlined

9 Apply linear, superficial and volumetric expansion equations to calculate expansion of liquids and metals

• 9.1Expansion processes for metals is defined
• 9.2Coefficient of linear expansion is outlined
• 9.3Linear expansion is applied to calculate machinery clearances and to shrink fit allowances
• 9.4Superficial and volumetric expansion of solids is calculated and recorded
• 9.5Apparent expansion of liquids in tanks is calculated and recorded

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To satisfy the Principles of Assessment and Rules of Evidence, an assessment for MARL043 needs to address all 84 unit components: 9 elements with 50 performance criteria, 7 performance evidence requirements, 27 knowledge evidence requirements, and the foundation skills. A coverage matrix mapping each question and task to these components is what an auditor looks for.

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