Refrigeration - Frederick M. Jones
Bureau of Standards: An organization that establishes and promotes standards for various industries.
Compression: The act of applying pressure to reduce the volume of a substance.
Condenser coils: Coils located on the outside of a refrigerator where the hot refrigerant gas is cooled so it will turn back into a liquid.
Diesel engines: Engines that use diesel fuel.
Evaporation: The process in which a liquid turns into a gas.
Evaporator coils: Coils located on the inside of a refrigerator where the refrigerant absorbs heat from inside the refrigerator.
Expansion device: A component that controls the flow of refrigerant and helps regulate temperature in the system.
Insulation: Material used to prevent the transfer of heat or cold.
Kinetic energy: The energy of motion.
Ozone: A molecule made up of three oxygen atoms (O3) that helps protect the Earth from harmful ultraviolet radiation.
Patent: A legal protection granted to inventors that gives them exclusive rights to their invention for a certain period of time.
Perishable: Items, usually food, that are likely to decay or spoil quickly.
Refrigerant: A substance used in refrigeration systems to absorb heat and create cooling temperatures.
Refrigeration: The process of moving heat from one location to another in controlled conditions..
Synthesized: Created or produced by combining different elements or substances.
Vapor-compression: A process used in refrigeration systems that involves compressing and condensing a refrigerant to create cooling effects.
Refrigeration & Fred McKinley Jones
Refrigeration is a process of moving heat from one location to another in controlled conditions.
A refrigerator uses the evaporation of a liquid to absorb heat. It's all based on the following physics: - a liquid is rapidly vaporized (through lowering compression) - the quickly expanding vapor requires kinetic energy and draws the energy needed from the immediate area - which loses energy and becomes cooler. Cooling caused by the rapid expansion of gases is the primary means of refrigeration today. The liquid, or refrigerant, used in a refrigerator evaporates at an extremely low temperature, creating freezing temperatures inside the refrigerator.
The history of artificial refrigeration began when Scottish professor William Cullen designed a small refrigerating machine in 1755. Cullen used a pump to create a partial vacuum over a container of diethyl ether, (C2H5)2O which then boiled, absorbing heat from the surrounding air. The experiment even created a small amount of ice. Though a method had been discovered for cooling substances it was not commercially practical at the time and no widespread processes had been invented.
During the early 1800s, consumers preserved their food by storing food and ice purchased from ice harvesters in iceboxes. The technology did not progress but iceboxes were used until nearly 1910.
In 1911, GE released a household refrigeration unit that was powered by gas. The use of gas eliminated the need for motor and decreased the size of the refrigerator. However, electric companies that were customers of GE did not benefit from a gas-powered unit. Thus, GE invested in developing an electric model. In 1927, GE released the Monitor Top, the first refrigerator to run off electricity.
In 1930, Frigidaire, one of GE’s main competitors, synthesized Freon (CF2Cl2). With the invention of synthetic refrigerants, safer refrigerators were possible for home and consumer use. In the 1970s, though, the compounds were found to be reacting with atmospheric ozone, an important protection against solar ultraviolet radiation, and their use as a refrigerant worldwide was curtailed in 1987.
Probably the most widely used current applications of refrigeration are for air conditioning of private homes and public buildings, and refrigerating foodstuffs in homes, restaurants and large storage warehouses. The use of refrigerators in kitchens for storing fruits and vegetables has allowed adding fresh salads to the modern diet year round, and storing fish and meats safely for long periods. Optimum temperature range for perishable food storage is 37 - 41 °Fahrenheit (3 to 5 °Celsius/Center grade).
Dairy products are constantly in need of refrigeration, and it was only discovered in the past few decades that eggs needed to be refrigerated during shipment rather than waiting to be refrigerated after arrival at the grocery store. Meats, poultry and fish all must be kept in climate-controlled environments before being sold. Refrigeration also helps keep fruits and vegetables edible longer.
Heat naturally flows from hot to cold. To make a refrigerator function, you must reverse this natural process and make heat flow to heat and cold flow to cold. This is physically impossible to do directly. In order to make a refrigerator work, the system has two separate components one in which heat flows to cool in the exterior of the system and make heat flow to cool ion the interior part of the system.
The difference between them is that on the exterior part of the system, the temperature of the heat source is much higher than in the interior part of the system which you are trying to keep cool.
This consists of a refrigeration cycle, where heat is removed from a low-temperature space or source and rejected to a high-temperature location with the help of external work.
A refrigeration cycle describes the changes that take place in the refrigerant as it alternately absorbs and rejects heat as it circulates through a refrigerator. It is also applied to heating, ventilation, and air conditioning HVACR (Heat-Ventilation-Air Conditioning-Refrigeration) work, when describing the "process" of refrigerant flow through an HVACR unit.
Work is applied to cool a living space or storage volume by pumping heat from a lower temperature heat source into a higher temperature heat location. Insulation is used to reduce the work and energy needed to achieve and maintain a lower temperature in the cooled space.
The vapor-compression cycle is used in most household refrigerators as well as in many large commercial and industrial refrigeration systems.
The Vapor-Compression System
In the refrigeration cycle, there are five basic components: fluid refrigerant; a compressor, which controls the flow of refrigerant; the condenser coils (on the outside of the fridge); the evaporator coils (on the inside of the fridge); and something called an expansion device. Here’s how they interact to cool your food.
The compressor constricts the refrigerant vapor, raising its pressure, and pushes it into the coils on the outside of the refrigerator.
When the hot gas in the coils meets the cooler air temperature of the kitchen, it becomes a liquid.
Now in liquid form at high pressure, the refrigerant cools down as it flows into the coils inside the freezer and the fridge.
The refrigerant absorbs the heat inside the fridge, cooling down the air.
Last, the refrigerant evaporates to a gas, and then flows back to the compressor, where the cycle starts all over.
People in cities are heavily dependent upon remote locations in order to obtain their food for daily consumption. How to get that food there without it spoiling was a problem.
…and then along came Jones
Frederick McKinley Jones was born in Cincinnati, Ohio on May 17, 1893. At an early age, Fred demonstrated a great interest in mechanical things, whether taking apart a toy, a watch or a kitchen appliance. Eventually he became interested in automobiles.
At the age of twelve, he began working sweeping up at a garage. He spent much of his time observing the mechanics, and that, along with an appetite for learning through reading developed within Fred an incredible base of knowledge about automobiles.
In 1912, at the age of 19, Jones moved to Hallock, Minnesota, where he worked as a mechanic.
On August 1, 1918 Jones enlisted in the 809 Pioneer Infantry of the United States Army and served in France during World War I. While serving, Jones recruited German prisoners of war and rewired his camp for electricity, telephone and telegraph service.
In 1919, Fred returned to Hallock.
Over the next few years Fred began tinkering with almost everything. When one of the doctors he worked for on occasion complained that he wished he did not have to wait for patient to come into his office for x-ray exams, Jones created a portable x-ray machine that could be taken to the patient. Unfortunately, like many of his early inventions, Jones never thought to apply for a patent for machine.
In 1927, Jones was faced with the problem of helping friend convert their silent movie theater into a “talkie” theater. Not only did he convert scrap metal into the parts necessary to deliver a soundtrack to the video, he also devised ways to stabilize and improve the picture quality. When Joe Numero, the head of Ultraphone Sound Systems heard about Fred’s devices, he invited Fred to come to Minneapolis for a job interview.
Despite the fact the company's receptionist reportedly told 38-year old Jones on arrival for the interview that "We don't have any jobs for a colored boy," Numero offered Jones a job as an electrical engineer.
Around 1935, Jones designed a portable air-cooling unit for trucks carrying perishable food. Before Jones' invention, the only way to keep food cool in trucks was to load them with ice.
In 1938 a golfing buddy of Numero's complained of problems his business was experiencing with heat-related loss of perishables during transport. To Numero's surprise, the friend later brought a truck to Ultraphone, challenging Numero and his engineers-one of whom was Fred Jones-to create a refrigerated truck. Later that year, Jones and Numero co-founded the U.S. Thermo Control Company of Minneapolis, later known as Thermo King.
Jones was given the task of developing a device that would allow large trucks to transport perishable products without spoiling. Jones set to work and his automatic refrigeration system, and transformed the shipping and grocery businesses.
This landmark invention ushered in the era of frozen foods, large supermarkets and the restaurant industry as we know it today. Refrigerated transport also made the delivery of fresh produce anywhere in the country a possibility, regardless of the season. The concept of continuous cooling of perishables is often referred to as the "Farm to Fork" cold chain.
In 1938, Numero founded a new venture: the U.S. Thermo Control Company (later to become Thermo King). Jones served as vice president of engineering. One year later, Jones filed for Thermo Control’s first patent: the Model A, the world’s first successful system for refrigerated transportation.
1939 - Around this time, Fred came up with a new idea – an automatic ticket-dispensing machine to be used at movie theaters. Fred applied for and received a patent for this device in June of 1939 and the patent rights were eventually sold to RCA.
The Model A. developed in 1939 was designed to be mounted onto the undersides of semi-trucks and to pass refrigerant tubing to their trailers. The Model A worked, but it was heavy and bulky.
The real breakthrough came with the Model C. The refrigeration unit was placed at the front top of the trailer where it remains to this day.
During World War II, Thermo King made Model Cs exclusively for the U.S. military. The military applied the invention to boats, planes, and trucks in order to transport temperature-sensitive drugs and blood plasma to soldiers in need.
The Model C became commercially available after World War II and immediately made an impact on the agricultural industry. Jones’ invention laid the groundwork for the modern supermarket.
1944 - Jones became the first African American to be elected into the American Society of Refrigeration Engineers.
1948 - Building on existing technology, Thermo King developed refrigerated box cars for use in rail transport.
1949 - Thermo King was a $3 million business.
During the 1950s he was a consultant to the U.S. Department of Defense and the Bureau of Standards.
1956 - Thermo King air conditioning units are installed in passenger buses.
1958 - Thermo King incorporated diesel engines into refrigerated units.
February 21, 1961 - Frederick McKinley Jones passed away.
During his life, Jones was awarded 61 patents. Forty were for refrigeration equipment, while others went for portable X-ray machines, sound equipment, and gasoline engines.
STEM Topic 18: PROBLEM SET - 1
A refrigeration unit cools down an insulated truck trailer at a rate of 2 degrees Fahrenheit per hour. If the room's initial temperature is 80 degrees Fahrenheit, how long will it take for the trailer truck to reach a temperature of 50 degrees Fahrenheit?
A refrigerated container is set to maintain a temperature of -10 degrees Celsius. If the outside temperature outside the container is 25 degrees Celsius, what is the temperature difference in degrees Fahrenheit?
Note: Celsius= 5/9(Fahrenheit-32)
A mobile refrigeration unit operates at an average power consumption of 2.5 kilowatts per hour. If it runs for 8 hours a day, how many kilowatt-hours of energy does it consume in a week?
A refrigeration system requires 3 kilowatts (kW) of power to maintain the desired temperature. If it operates for 6 hours, how many kilowatt-hours (kWh) of electricity does it consume?
A refrigerated display case has a length of 5 feet, a width of 3 feet, and a height of 4 feet. What is the total volume of the display case in cubic feet?
A refrigeration unit has a refrigerant leak rate of 0.5 ounces per week. If the unit operates for 4 weeks, what is the total refrigerant lost in pounds?
1 liter = 61 cubic inches (rounded to the nearest whole cubic inch).
A mobile refrigeration unit has a maximum capacity of 500 liters. If it is currently holding 350 liters of perishable goods, how much more can it accommodate?
A refrigeration technician charges $80 for a service call, plus $50 per hour for labor. If the technician spends 3 hours repairing a mobile refrigeration unit, how much will the customer be charged?
A refrigerated storage room measures 10 feet by 8 feet by 6 feet. What is its total volume in cubic feet?
A container with 2 liters of liquid nitrogen is left open. Each hour, 10% of the liquid evaporates. How much liquid nitrogen will be left after 4 hours? Round answer to one decimal place.
The temperature outside is -10 degrees Celsius. If water freezes at 0 degrees Celsius, how much colder is it outside compared to the freezing point of water
A pot of water has 500 milliliters (ml) of water. After boiling for some time, it evaporates and reduces to 300 ml. How much water evaporated?
The freezing point of a certain solution is -20 degrees Celsius. If the temperature is currently -10 degrees Celsius, how many degrees away from the freezing point is it?
Answer: It is 10 degrees away from the freezing point.
A puddle of water has a volume of 500 cubic centimeters (cm³). Due to evaporation, it reduces to 350 cm³. How much water evaporated?
A mobile refrigeration truck has a fuel tank capacity of 60 gallons. If it consumes fuel at a rate of 2 gallons per hour, how many hours can it operate before needing to refuel?
The British Thermal Unit (BTU) is a measure of heat, which is measured in units of energy. It is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
A refrigeration system has a cooling capacity of 10,000 BTUs per hour. If the system operates for 6 hours, what is the total cooling capacity generated in BTUs?
A Watt is a measure of the rate of energy transfer over a unit of time.
The Energy Efficiency Ratio (EER ) multiplied by the power input (in watts) gives the cooling capacity in BTUs. The higher the EER rating, the more efficient is the air conditioner.
A refrigeration system operates at an energy efficiency ratio (EER) of 12. If the system consumes 1000 watts of electrical power, what is the cooling capacity in British Thermal Units (BTUs)?
The Coefficient of Performance or (COP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency. COP multiplied by kilowatts gives the output.
A refrigeration compressor has a coefficient of performance (COP) of 3.5. If the compressor consumes 2 kW of electrical power, what is the cooling effect in kilowatts?
A refrigeration unit operates at a coefficient of performance (COP) of 4.5. If the unit consumes 2,000 watts of electrical power, what is its cooling capacity in watts?
The freezing point of ethanol (C2H6O)is -114 degrees Celsius. If the temperature is currently -80 degrees Celsius, how much warmer is it than the freezing point of ethanol?
A refrigeration system removes 25,000 British Thermal Units (BTUs) of heat per hour. If it operates for 5 hours, what is the total amount of heat removed in BTUs?
A refrigeration unit has a refrigerant charge of 10 pounds. If it loses 2.5 pounds of refrigerant due to leakage, what is the remaining refrigerant charge?
A mobile refrigeration unit operates at a temperature of -5°C. What is this temperature in degrees Fahrenheit?
A refrigeration system has a refrigerant leak rate of 0.1 ounces per day. If the system operates for 2 weeks, how much refrigerant is lost in pounds?
STEM Topic 18: PROBLEM SET - 2
The cooling capacity (C) of a refrigeration unit is directly proportional to the power input (P) and inversely proportional to the temperature difference (ΔT). If a unit with a power input of 800 watts has a cooling capacity of 2000 BTU/h when the temperature difference is 10°F, find the cooling capacity when the temperature difference is 5°F.
The energy efficiency ratio (EER) of a refrigeration system is defined as the cooling capacity (C) divided by the power input (P). If a system has an EER of 12 and a cooling capacity of 2400 BTU/h, find the power input.
The refrigerant charge (R) of a refrigeration unit is inversely proportional to the leakage rate (L). If a unit with a refrigerant charge of 10 pounds has a leakage rate of 0.05 pounds per day, find the refrigerant charge after 1 week.
The temperature inside a refrigerated space decreases at a constant rate of 2°F per hour. If the initial temperature is 50°F, write an equation to represent the temperature T after h hours.
The power consumption (P) of a mobile refrigeration unit is directly proportional to the operating time (t) and inversely proportional to the energy efficiency ratio (EER). If a unit with an EER of 10 consumes 200 watts of power when operating for 4 hours, find the power consumption when operating for 6 hours.
The cooling capacity (C) of a refrigeration system is directly proportional to the refrigerant charge (R) and the temperature difference (ΔT). If a system with a refrigerant charge of 8 pounds has a cooling capacity of 4000 BTU/h when the temperature difference is 20°F, find the cooling capacity when the temperature difference is 10°F.
The refrigerant charge (R) of a mobile refrigeration unit is directly proportional to the volume (V) of the refrigerated space. If a unit with a refrigerant charge of 5 pounds can refrigerate a space with a volume of 100 cubic feet, find the refrigerant charge for a space with a volume of 150 cubic feet.
The power input (P) of a refrigeration unit is directly proportional to the refrigerant charge (R) and the cooling capacity (C). If a unit with a refrigerant charge of 6 pounds has a power input of 600 watts when the cooling capacity is 3000 BTU/h, find the power input when the cooling capacity is 4000 BTU/h.
The temperature inside a refrigerated space increases at a constant rate of 3°F per hour. If the initial temperature is 60°F, write an equation to represent the temperature T after h hours.