Personal thoughts on refrigeration

Refrigeration extends the amount of time that things such as milk, meat, and medicine can be stored. People now have access to a wider variety of food than ever before. Refrigeration increases the supply of food, which decreases the price. Consequently, it is possible for people with even the lowest wages to have healthy diets. Because of improved nutrition, refrigeration played a role in the increase of average American height around the turn of 20th century. Less food is wasted as a result of being able to keep items longer in refrigerators. Preventing food waste can improve the environment since decomposing food releases carbon dioxide. The biggest drawback to refrigeration is the carbon footprint it produces because of energy use. However, without refrigeration  more food would need to be produced to replace spoiled food. And, food production has a bigger environmental impact than refrigeration. One way to reduce the environmental impact caused by refrigeration is to use other energy sources than fossil fuels. Another is to purchase food that is produced locally so that greenhouse gas emissions caused by transportation are reduced. The other negative effect of refrigeration is that the HFCs used as refrigerants have a large impact on global warming. The next step in refrigeration improvements is to develop refrigerants that will not have as big of an environmental impact. Although there are some negatives to refrigeration, they are far out-weighed by the benefits. Overall, refrigeration is a great technology that improves the quality of life.

Environmental Impacts

The biggest environmental impact of refrigeration is energy consumption. Refrigerator motors must run day and night and therefore use more energy than any other home appliance. However, since refrigerator energy efficiency standards were imposed in the 1970′s, energy use has decreased by two-thirds and the price has decreased by half. Although, it is important to note that home refrigerator size increased by 10%. The typical American family refrigerator consumes about 38 kJ of energy per week. This may seem like a lot, but it is important to consider the alternatives. Refrigeration preserves products for considerably longer than shelf-life or other preservation techniques. Food production has a much bigger environmental impact than refrigeration. Without refrigeration, there would be significantly more food waste and it would be necessary to produce even more food.

Another environmental impact comes from the chemicals used as refrigerants. Stable, nonflammable chlorofluorocarbons (CFCs) began being used in the 1930′s to replace less stable, more toxic refrigerants. However in the 1970′s, it was discovered that CFCs were depleting the ozone layer. In 1987, the Montréal Protocol banned the use of CFCs. Hydrofluorocarbons (HFCs) have since replaced CFCs as refrigerants. HFCs do not harm the ozone layer, but they are potent greenhouse gases. In 2005, HFCs were responsible for 17% of the total global impact on climate change. Most HFCs enter the environment through leaks, servicing, and disposal of refrigerators (industry only contributes about 10% to HFC emissions).

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CFC free water bath in LS 428

Dates and figures from “Refrigeration Nation: a History of Ice, Appliances, and Enterprise in America” by Jonathan Rees (2013).

Personal Thoughts on Refrigerators

Refrigerators have improved the quality of life for humans. They allows food to be kept over longer periods of time resulting less food going to waste. Most of the negative effects of the refrigerator do not come from the refrigerator itself, rather it  comes from the source of energy for the refrigerator. Therefore most of the negative effects could be reduced by simply changing the energy source to something more environmentally friendly (i.e. solar power).

My personal thoughts on refrigeration

Prior to modern refrigeration the most common ways to keep meat and other short term food items from spoiling were to salt or use large blocks of ice from mountainous areas to preserve the food items. With the implementation of the refrigeration it allowed more people to be able to afford to store food, and with that the push to innovate a way to mass produce and make the refrigerator and freezer available to all walks of life. From there the common man now has access to a simple yet effective means of storing food and can spend more time on a wider variety of pursuits.

-Steven Schmitz

Burning Solid Wastes

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Rubber is essentially composed of hydrocarbon compounds with large molecular weights. A model of heat of combustion was created starting with methane and adding carbons. Paper is made of glucose polymers (cellulose). Another model of heat of combustion was made starting with glucose and adding more glucose compounds. Recursive formulas were generated for increasing each carbon chain. As more carbon is added to rubber, the amount of energy released per mole decreases. As more carbon is added to paper, the amount of energy per mole increases. Each approaches an asymptote. For hydrocarbons (rubber) this is about -35 kJ/g and for carbonhydrates (paper) it is about -27 kJ/g.

Thermodynamic Principles behind Refrigerators

refrigerator

Figure 1 shows the Clausius statement of the 2nd law of thermodynamics: heat cannot move from cold to hot unless work is done to the system. Figure 2 is a basic schematic of a typical refrigerator. 

Refrigerators work according to the Clausius statement of the second law of thermodynamic (Figure 1) that states that it is impossible for heat to move from a cold reservoir to a hot reservoir without work being done to the system.  A basic schematic of a typical refrigerator (Figure 2) illustrates this.From Valve 1 to Valve 2 (red; heat reservoir), the refrigerant is in a liquid form and releases the heat from the inside of the refrigerator to the outside (ie the kitchen). At valve 2, the expansion valve, the refrigerant is changed from a liquid to a vapor and pushed back inside the refrigerator. From valve 2 to the Compressor (blue, cold reservoir) the refrigerant, in vapor form, absorbs energy (ie. heat inside the refrigerator). At the compressor, work is done to the refrigerant to change it from a vapor to a liquid. The refrigerant is then pushed out of the refrigerator towards valve 1 and the process starts over.

Introduction

Hello all! I’m Sarah Larson, a senior Chemistry Major with minors in Human Biology and Dance. I currently work on campus as a Student Ambassador and as a Lab Assistant. When I’m not busy with work and school (which is very rare) I spend most of my time dancing either at Ballroom Club or in the studio.