Featured Article » Nonfiction

Refrigeration and the 1632 World: Opportunities and Challenges

Written by Mark H. Huston

Barflies have an amazing working knowledge on a lot of subjects. They are, on the whole, a bunch of pretty bright people, having great fun playing at this "what-if" exercise that is Eric Flint's 1632 universe. Hanging out in cyberspace, and in real life with some of these 'flies, has been an educational, intellectually stimulating, and an occasionally intellectually humiliating, experience. While putting this article together, I have learned more than just the basic history of refrigeration, which by itself is fascinating. (In fact, I knew quite a bit to start before I started this, but that is another story.) I have learned much more about how truly complex life really is.

It has been said that it is a truly wise man who realizes that the things he does not know are far, far more important that what he truly does know. I have finally figured out what that means.

As one of those (hopefully) bright barflies, I can come up with a pretty good technical argument and occasionally spin a halfway acceptable yarn. Occasionally even contribute! But I was unprepared for the "AH-HA" moment that hit me during the third rewrite of this article. That "AH-HA" is this.

We do not know what we do not know.

We do not even know what questions to ask.

We are unconsciously unaware incompetents.

In all things associated with this universe—up to the "AH-HA" anyway—I seriously and consistently underestimated the complex interdependence of industry, suppliers, and processes, which make up our modern world. If I need to order five gallons of ammonia, or thirty pounds of R-22, I do not have to invent that infrastructure to make everything from the containers the material is shipped in to the tires on the delivery truck. It is beyond the comprehension of any single individual. Even the most talented engineers you know couldn’t do it. The young and aggressive ones would think they could, but the wise ones would know better.

Doing what needs to be done in this fictional world is hard. Even those tasks that we consider easy to do. For Grantville to survive and prosper, up-timers and down-timers will need to recreate the systems and that web of interdependence. Mike Stearns is right. Open the library to all comers. It is impossible to do otherwise.

So when you are kicking back on the sofa after reading one of the many Gazettes, or some of Eric's original books, and the thought crosses your mind, "Why did they do it that way? That is silly. It would be easier if they just painted it blue, or built a sterling engine, or used a rigid design airship. . . ." Stop and think.

Think about what you do not know, and start from there.

In this article, we are going to discuss refrigeration, how the various processes actually work, and analyze the resources available to Grantville. We are also going to look at ways we can move major industries forward by utilizing existing refrigeration resources. Finally, we want to look at how we can develop down-time methods of refrigeration with down-time available technology and speculate on the market forces that will drive investments. We are also going to touch briefly on the process of air liquefaction, which is critical for industrial gasses.

Refrigeration is one of those things that nobody thinks about, but many processes and systems depend upon. It is nearly as critical to a technical and manufacturing economy as our famous nitric acid. A substantial portion of the refrigeration industry keeps food cool, chemical plants and refineries running specific processes, and operating rooms at the correct temperatures. Modern machining and manufacturing depends greatly on climate control.

Beer is important

Beer is as important to 1632 Germany as water is to a fish. It is the all-purpose beverage, one of the few liquids that will generally not give you some sickness after ingesting it. At least as long as it is not consumed in excessive quantity. Prior to refrigeration, beer could only be brewed until February or March, and then restarted in the fall. Wort cooling (an important step in the brewing process) could not be accomplished, as there was no supply of cooling that occurred naturally during those times of the year. Equipment was idle for parts of the year, not making any beer or money for the owners. As soon as down-time brewers hear about the magic process of refrigeration, there will be a stampede to acquire this technology. This "new" technology, combined with a better knowledge of yeast and its influence on the fermentation process is revolutionary.

Down-timers do not yet understand yeast and its function in the brewing process. Proper yeast fermentation temperatures are critical to a palatable beer. Up-timers can teach the Germans a thing or two about beer. If not flavor, then technique. There may be initial issues with German beer purity laws, as they did not take into account refrigeration and forbade summer production of beers. However, those rules were changed in OTL when refrigeration became the standard. And who says that any brewer in the USE has to follow those laws? Besides, that is Bavaria, and who listens to them?

The first practical vapor compression refrigeration system (there are several such claims with many variations), was developed and installed by Carl Paul Gottfried Von Linde in 1871, in Munich. It was for a brewery. It is conceivable that the brewing industry will invest heavily in this technology. (They gave Linde 70,000 florins after only reading his research paper!) I see no reason why the same thing would not happen again in this time line as in ours. Beer is important.

The other industry that drove refrigeration in OTL was ice. There was a tremendous infrastructure developed prior to refrigeration to cut ice from fresh bodies of water, store, and deliver it to market. Walden Pond was used as an ice harvest location. My grandmother called her refrigerator an "ice box." Two things killed the ice harvesting. The first was the pollution that increased in ponds and lakes made the harvested ice unsanitary. The second was the advent of vapor compression refrigeration. Vapor compression refrigeration was initially used in "icehouses" where ice was made year round. Later, icehouses were replaced by the electric refrigerator, which finally killed the home ice delivery industry.

The ice making and brewing industries drove the early refrigeration market in OTL, and the dynamics will be similar in the 1632 world.

However, there is another important factor to consider that did not happen in our time line. Seventeenth-century investors are simultaneously starting the chemical industry, petrochemical industry, pharmaceutical industry, steel industry, precision manufacturing and instrumentation industries, gunpowder industry, textile industries and electronics industries, to name a few.

And every one of those industries is reliant on refrigeration in some manner. Many could not exist without advanced climate or process cooling apparatus. Some can "get by" without it for a while. Steel is a good example.

Steel? Refrigeration is needed to make steel? Well, not exactly the steel itself. But without refrigeration, there will be no basic oxygen furnaces, and therefore fewer specialty steels. Refrigeration is needed to extract the oxygen from the air, along with argon, helium, nitrogen and other gasses. We cannot even use our oxy-acetylene torches until we develop an economical process to separate the oxygen out of the air, which will generally require refrigeration. It can be made by electrolysis and capturing the oxygen from the process, but that provides wet oxygen that is more difficult to use.

Unlike OTL, the demand for refrigeration and air conditioning is going to be explosive. This dynamic economy will have a need for the existing refrigeration resources of Grantville to quickly develop the brewing, ice, and cold storage industries. This means your small home air conditioning system will be worth quite a bit, possibly more than the home and land that it services. This may satisfy a few small prototype industrial applications, or possibly the Captain General's new palace in Magdeburg, but the demand will be strong. Far stronger than the number of viable systems in Grantville.

The challenge will be to best utilize existing resources, such as home systems, supermarket refrigeration, automobiles, restaurants, slurpee machines and even home refrigerators. We will need refrigeration that can operate without electrical power, while at the same time we develop new sources of refrigeration from the 1632 tech base.

The technology will not have the luxury to gradually evolve with the industries it serviced, like in OTL. Instead of evolving gradually over a period of fifty years, we are going to need cooling almost instantly, across a wide range of industries.

Before we get too far with all of these applications, let's learn a little more about the different refrigeration processes and how they work.

What is Refrigeration?

In its simplest form, it is the controlled movement of heat from one location to another. When you are cooling something, you are removing heat from one location, and are relocating it to another. That is why it is cool in the house and the condensing unit (the box with the fan on it) outside the house has all of that hot air blowing out of it. We are just moving the heat around. There are whole bunches of ways to accomplish this. The two main methods are vapor-compression and absorption. From there the options take off to an almost infinite number of permutations and modifications.

"Refrigeration" is the process of mechanically moving heat from one place to another. "Air Conditioning" is controlling the temperature and humidity in an occupied space. Many times, refrigeration is used in the air conditioning process.

In the United States, the amount of refrigeration that any particular machine is producing is stated in "tons" of refrigeration. This has nothing to do with ironclad displacements, but is based roughly on a ton of ice.

In the early days of refrigeration, if you owned a theater, you wanted it cool. Early theaters (and other buildings) were cooled with ice. If you go to one of these old vaudeville houses that became a movie theater, you will notice little vents in the floor. Many times they put lighting in them now.

Underneath the rows of seats, there were blocks of ice that were placed in front of large fans, sometimes steam powered fans. As the air left the fans, it blew across the ice and cooled down. It then was discharged out of the little vents in the floor.

If you wanted to sell a theater owner a machine to take the place of his ice (which he ordered by the ton) you would want to give him the equivalent rating.

“How many tons of ice will I get out of this, Mr. Carrier?"

“This is a thirty ton machine, Mr. Ziegfeld.”

This measurement was a brilliant marketing tool, which bridged the gap between ice delivery and the newfangled refrigeration process. It made the mysterious (and sometimes dangerous) technology accessible.

Today we are looking at a ton as 12,000 BTU/hr. Equipment selection is based on rate of heat removal. And 12,000 BTU/hr is about how much cooling you will get from a two thousand pound block of ice as it melts.

How does refrigeration move the heat around?

It was discovered that if you took a high-pressure liquid, and released it through a controlled opening that allowed the liquid to flash (change from a liquid) to gas at a lower pressure, a cooling effect was created. There is a fixed relationship between the liquid state of a material, the gaseous state of a material, the pressure surrounding the material and the temperature. The manipulation of these factors creates the refrigeration effect.

By changing the pressures, a refrigerant can move between the liquid and gaseous states. The liquid, changing state to a gas, requires energy, so it grabs it from the surroundings. The net result is cooling. How does that work? Well, it is pretty simple actually.

For example, we have a tank of liquid CO2 (carbon dioxide). It is at 1000 PSI (pounds per square inch) of pressure. When we open a valve on the bottom of the tank, what is going to happen?

Well, we will have a bunch of CO2 that starts out as a liquid, and now because of the relative low pressure, it really needs to be a vapor. The only way it will become vapor is for it to grab heat from the surroundings. Our valve on the liquid CO2 will become very, very cold as the escaping gas gets its energy from the surroundings. Voila, instant refrigeration.

This works great until the CO2 tank is empty, then the refrigeration stops. In technical language, this is called an open refrigeration system. There is no way to repeat it unless you get another cylinder of CO2.

This is the same thing that happens at a higher temperature if you remove the radiator cap on an overheated engine. The typical automobile engine cooling system is pressurized to around 15PSI. That pressure keeps the water from boiling. When the cap is opened, steam sprays out of the opening, not hot water. That is why they say never to open a radiator cap when the engine is hot. With the pressure released, the 250DegF liquid is going to rapidly boil, and as it expands it sprays out the opening. It creates an instant unpleasant and burning steam bath. It is absorbing heat from the engine as it flashes to steam.

Think about an aerosol can. If you use the pressurized can non-stop, it rather quickly grows cold. When the propellant is exhausted, the process stops. This is called an open refrigeration system, because none of the components are recovered.

If the above is called an open refrigeration system, then the one that we want is going to (obviously) be called a closed refrigeration system. A closed system is one that uses the refrigeration effect of a high-pressure liquid that changes state to a gas, creates a cooling effect, and then recaptures and condenses the vapor back to a liquid as it rejects the accumulated heat. Your household refrigerator is a closed vapor compression system.

It turns out that this phenomenon works both ways, up and down. When you increase the pressure on a vapor, it will condense and release all of the heat gathered while it was changing state the first time. Hence the warm air blowing out of the box outside the house.

Absorption Refrigeration

Absorption is what is used in RV refrigerators, or in some large-scale chillers and process applications. It has a single and substantial advantage over vapor compression. In smaller sizes, there is no need for a motor drive, only the application of heat to the system. You read that right, heat to a system to make cooling.

This chemical process was actually the first refrigeration. Thomas Cullen was exploring the nature of gasses in a vacuum in 1748. Initially, he got water to boil at room temperature by reducing the pressure in an enclosed vessel. Later, his device consisted of a pair of vessels connected with a pipe, with one vessel containing water, and the other containing sulfuric acid. When a deep vacuum was placed on the chambers, and the acid chamber was agitated, the water in the adjoining chamber evaporated and was absorbed by the strong acid. As the water changed state from a liquid to a gas, a refrigeration effect was created. The water chamber would actually freeze. When the acid became diluted with water vapors, the process stopped. Unfortunately, nothing practical was done about with his invention until 1850, when the first of the Carre brothers built a practical machine in France.

The first practical absorption machine used Cullen's sulphuric acid and water. The second brother patented the ammonia/water absorber in America in 1859. These machines made their way around the world. There were several in the United States when ice shipments from the North were stopped during the American Civil War. The southern states imported several of the machines. What is very interesting about the Carre machines is that they were able to operate with no energy input with the exception of heat, and some manual manipulation. A history described the operation of the machine in 1880 Texas as, it had "a furnace that was fired with chips and kindling wood, to heat the aqua ammonia." It was an entirely manual operation. That is important for any "off grid" operation of refrigeration. Heating and agitation of the absorbent are accomplished manually.

On a large-scale installation a perplexed operator once described it to me, as "This is impossible. Steam goes into the top of the machine, and cold water comes out the bottom!" It admittedly is somewhat counter-intuitive.

But that is basically how absorption refrigeration works. You apply a heat source to the absorption refrigeration cycle, and cooling is produced. Many smaller systems such as in RVs, use ammonia as the refrigerant, and water as the absorbent. Large-scale absorbers, that would be large enough to cool a fifty-story high-rise office building for example, are operated with water as the refrigerant, and lithium bromide (a strong salt solution) as the absorbent. These came into widespread use in the early 1950's in OTL.

I know absorption seems difficult to understand on the surface. But bear with me. Instead of a compressor inside this machine, there is a chemical reaction taking place. Ammonia is attracted to water. The same is true for salt and water. Think of a saltshaker during high humidity. The salt absorbs moisture from the air. The result is that your salt clumps up in the shaker. The same sort of thing goes on inside an absorption machine. This chemical reaction of absorption acts as the removal process for the refrigerant vapor, sort of like the inlet of the compressor in vapor compression. The refrigerant and absorbent are then pumped to a heat source and separated. From there they return to their respective areas of the machine and begin the cycle again.

The 1911EB describes the process wonderfully. It says that the absorbent "becomes greedy" for the refrigerant. Not an exact technical description of the process, but one that certainly captures the spirit.

Continuous Process and Generating Cycle Absorption

There are two main types of absorption refrigeration. There is the continuous process, and the generating cycle method. The simplest and most basic is the generating cycle method. With this, a heat source is set to the device (usually very small) once and then removed. After being heated for a period of time, it becomes "charged." The charging process separates the ammonia (refrigerant) from the water (absorbent), and allows the system to start the refrigeration process. Gradually the ammonia inside changes state from a liquid to a gas in the evaporator, creating the cold. It is then re-absorbed into the water. The next cycle (usually the next day) it is charged (heated and separated) again. Thomas Cullen's sulphuric acid device was one such system, although to charge it, the sulphuric acid was replaced, instead of being heated and separated.

For the 1632 universe, the generating cycle offers some interesting opportunities. This has a simple operation, and something the size of a small suitcase could provide refrigeration on a daily basis for food transport or home refrigeration, particularly where there is no electrical service. It opens up tremendous flexibility to the existing food transport and storage business on a smaller scale. These systems are generally very small, and can only provide a constant load. Think of them as a portable 10 pound bag of ice, which refreezes after it is used.

Unfortunately, like most things, simple operation on the surface usually means that it is more complex and well designed beneath the surface. And how would anyone in Grantville know about this process?

This process was widely used in the late 1920's as a household appliance, transitioning between the periods where ice was delivered to homes, to modern vapor compression refrigeration. It was called a Crossly IceBall. The only way that it could be reproduced is if there is an old unit lying around somewhere, which is unlikely. It is possible that it could be developed, but the developers would need a lot of research money and time. If an old timer remembered it, just from the concept, development would be very difficult. And remember, this cannot be scaled up much beyond a few pounds of ice making per day, per unit.

Besides the internal complexity, it needs to withstand pressures of over 300PSI. This will push the envelope of construction techniques for our early modern refrigeration researchers. If the oil fields and the boiler shop can build sufficient small pressure vessels then this is a possibility. And only uses a little bit of ammonia. While this process is neat, it is doubtful that the product will be rediscovered.

The other absorption process that uses ammonia is the continuous cycle. These are the machines that the Carre brothers developed. It is also something that is familiar to the population of Grantville. This is the more common RV refrigerator. This too will be mostly a small-scale operation in Grantville for similar reasons. It can, however, develop temperatures well below freezing. There are two blind spots in this method: Internal pressures and a mix ...