ENGR101 Week 1 Assignment Analysis
ENGR101 Assignment 3, 2014
Energy Units, Conversions and Estimation
The aim of this assignment is to further develop your skills in:
using and converting units
using an appropriate number of significant digits
estimating values
writing down assumptions used in your calculations
checking that answers are sensible
calculations related to energy in various forms
This assignment is due at 5 pm on Friday 11 April. It is worth 8% of your final mark in
ENGR101. You may hand write the answers; there will be no extra marks for a wordprocessed answer. There is no need to write a full report, but your working and answers must be clear enough to enable a first year science or engineering student to understand what you have done …show more content…
No electronic submission is required.
Not all the required information is given. You are expected to use textbooks, the Internet, or observation to find other information. Reference all sources of information by writing the references with each answer where the information is used. You may just write internet references as a url rather than as a complete APA reference, e.g., http://en.wikipedia.org/wiki/Calorie. In this assignment, and in all engineering work, all answers are expected to have correct units with an appropriate number of significant figures. Some assumptions will be required, so some questions do not have a single correct answer. State your assumptions.
1.
A candy bar has a marked nutritional value of 350 kilocalorie. How many kilowatthours of energy will it deliver to the body as it is digested? Assume 100% conversion. How many hours can the same amount of energy keep a 100 W light bulb operating?
[2 marks]
2.
A solar hot water supply system requires 80 US gallons of warm water each day heated from 70 degrees Fahrenheit to 120 degrees Fahrenheit. How large a solar collector would …show more content…
(See http://canta.co.nz/features/the-unclear-nuclear-future-nuclear-power-for-new-z/ for more information) [5 marks]
7.
The blue ENERGY STAR® mark is a shortcut to identifying New Zealand’s most energy efficient products. Only the top 25% of products meet ENERGY STAR’s stringent energy efficiency requirements, so one can be sure the performance of the purchased products is of superior energy efficiency.
For heat pumps, in order to achieve the Energy Star, it must be able to perform efficiently at 2
°C, this is called H2 testing condition (previously H1, tested at 7 °C). This data is submitted to the Government agency EECA (Energy Efficiency Conservation Authority) with supporting evidence. The efficiency of a heat pump can be represented by the Coefficient of Performance (COP).
For a heat pump that produces 4 kW of the heat energy out for 1 kW of electrical energy in, plus 3 kW of heat energy transferred from outdoor environment, the COP is 4 (heat energy out/electrical power in). For an electric bar heater, gas heating and wood fire, the typical COPs are 1, 0.85 and 0.65, respectively.
Table 1. Performance and cost of heat pumps.
Heating
Cost of heat pump
Energy Units, Conversions and Estimation
The aim of this assignment is to further develop your skills in:
using and converting units
using an appropriate number of significant digits
estimating values
writing down assumptions used in your calculations
checking that answers are sensible
calculations related to energy in various forms
This assignment is due at 5 pm on Friday 11 April. It is worth 8% of your final mark in
ENGR101. You may hand write the answers; there will be no extra marks for a wordprocessed answer. There is no need to write a full report, but your working and answers must be clear enough to enable a first year science or engineering student to understand what you have done …show more content…
No electronic submission is required.
Not all the required information is given. You are expected to use textbooks, the Internet, or observation to find other information. Reference all sources of information by writing the references with each answer where the information is used. You may just write internet references as a url rather than as a complete APA reference, e.g., http://en.wikipedia.org/wiki/Calorie. In this assignment, and in all engineering work, all answers are expected to have correct units with an appropriate number of significant figures. Some assumptions will be required, so some questions do not have a single correct answer. State your assumptions.
1.
A candy bar has a marked nutritional value of 350 kilocalorie. How many kilowatthours of energy will it deliver to the body as it is digested? Assume 100% conversion. How many hours can the same amount of energy keep a 100 W light bulb operating?
[2 marks]
2.
A solar hot water supply system requires 80 US gallons of warm water each day heated from 70 degrees Fahrenheit to 120 degrees Fahrenheit. How large a solar collector would …show more content…
(See http://canta.co.nz/features/the-unclear-nuclear-future-nuclear-power-for-new-z/ for more information) [5 marks]
7.
The blue ENERGY STAR® mark is a shortcut to identifying New Zealand’s most energy efficient products. Only the top 25% of products meet ENERGY STAR’s stringent energy efficiency requirements, so one can be sure the performance of the purchased products is of superior energy efficiency.
For heat pumps, in order to achieve the Energy Star, it must be able to perform efficiently at 2
°C, this is called H2 testing condition (previously H1, tested at 7 °C). This data is submitted to the Government agency EECA (Energy Efficiency Conservation Authority) with supporting evidence. The efficiency of a heat pump can be represented by the Coefficient of Performance (COP).
For a heat pump that produces 4 kW of the heat energy out for 1 kW of electrical energy in, plus 3 kW of heat energy transferred from outdoor environment, the COP is 4 (heat energy out/electrical power in). For an electric bar heater, gas heating and wood fire, the typical COPs are 1, 0.85 and 0.65, respectively.
Table 1. Performance and cost of heat pumps.
Heating
Cost of heat pump