Eternal Winter and Auto Air Conditioners

THIS MORNING, I realized warm weather is just a few weeks away. In a drive to the grocery store, after a short stop for my favorite coffee blend... I noticed the ambient outside temperature was not driving my cell phone thermometer into the red. I thought, "Soon I’ll be hearing the faint clicking sound of my car’s air conditioner system clutch. It’ll be quietly turning off and on, regulating the cool coming from the dash air vents."

Automotive air conditioners are wondrous units. They first appeared in cars during the late 1940s. Using principles first applied by an inventor named Carl Von Linde, who worked in the late 1800s, these systems operate on the thermodynamic principles of condensation, evaporation, and pressure changes.

 First we find it is true that God himself created that a fluid absorbs heat as it vaporizes. If you put a small quantity of alcohol on the back of your hand, as the alcohol evaporates away it reduces the temperature of your skin to the vaporization temperature of the fluid. You’ll feel the cooling effect.

 Now keeping that knowledge in mind, second we find the principle of vapor condensation. If you remove enough heat from a vapor it condenses. It becomes a liquid. For example, water vapor in the air condenses on the surface of a beer mug as the atmosphere surrounding it gives up heat. As a Lutheran minister, knowing that Brother Martin Luther and his wife made beer in Germany, clear back in the 1500s… I think even he may have known this little fact.

 In air conditioning, we put these natural principles to work. You see, working like Satan… a belt-driven compressor aggravates the vapor and puts your air conditioner into operation. The compressor is basically a hellish, hot heat pump. Don’t touch the outlet hose of a compressor with your bare hand! Even a sinful mechanic worth a beer keg knows, the engine drives the compressor's pistons and they make the vapor hot. Like Satan, the compressor is a demon which drives us… pushing us when we think we are hot… cooling us like we’ve got it all together.

 Driven by a car engine’s accessory belt and an electrically operated clutch in answer to a dashboard switch, the compressor pumps the heated refrigerant vapor. The compressor pumps like a demon squeezing your carnal appetites, so pressures rise to approximately 200-250 psi. Being put under that high pressure, the heat in the vapor concentrates into a very tight space. Like ourselves when we are pushed hard, the temperature of the gas rises. Also, the heat from the mechanical energy of the compressor whips things even higher.

 Pumped through a high-pressure rated hose and muffler that quiets the compressor pistons’ pulses, the  hot vapor enters the automobile’s condenser. The finned condenser rides behind the grille of the vehicle, just in front of the engine's radiator. That condenser functions a bit like that Bible you should read at home or at Church. Within it, evil heat gets cooled.

 You see, the refrigerant flows through finned cooling tubes of the condenser. The air flow around the outside of the fins when the car is moving or a temperature-controlled fan spins. The vapor therefore becomes a high-pressure liquid because it loses heat.

Now, we ask Linde's students… “What can be done with this cool, highly pressurized liquid?” Well, it’s a bit like when we are called to stand when baptized in a cold, flowing river. The liquid routes through a receiver-drier containing desiccant material. This removes the water. Like the sweat on your brow that can get in your eyes, here the valves of the system can get nasty. The metal can react with the chemistry of the refrigerant to produce acids. Acids will deteriorate system all air conditioning circuit components.

The now highly-pressurized liquid in the system flows from the condenser toward the evaporator through the high pressure hose, flowing to a regulator that meters the refrigerant into the cooling tubes of the evaporator. There, an orifice or valve action acts like the Holy Spirit. It convicts and lowers that rather sinful, hot high pressure so it can dissipate through the tubes of the evaporator unit. At the evaporator, air from the car’s interior blows across the outer surface of its finned tubes. This causes that high-pressure fluid inside the aluminum tubes to boil and vaporize.

 The refrigerant thus absorbs the heat of the air passing around the evaporator tubes. Cooled air now flows to the passenger compartment through ducts in the instrument panel. But note! The pressure drop across the evaporator must be carefully controlled to ensure proper cooling, so moisture won’t freeze in the evaporator fins. This is the purpose of that inlet valve. The warmed liquid in the evaporator heated by the air in the vehicle, turns again to vapor and gets compressed again… and again, and again… as the devilish compressor cycles on and off... until we turn off the engine ignition and shut the whole thing down. See, brothers and sisters... we can tell Satan when and where to go!

P.S. It just started to snow. Watch this...

 

 Now, may he peace of God that surpasses all human understanding, keep your hearts and minds in Jesus Christ our Lord.