Saturday ride.

I've been chomping at the bit to get outside and ride my bike. I really took to riding last year when I realized that changing my job to work for an entitiy that stays in one spot means I could ride my bike to work rather than spending hard earned money on gas every week. Plus it has helped me reduce my mass.

So, this morning I woke up and found it to be a balmy 42 degree Michigan morning. But no rain makes it an absolute bonus. I jumped on my bike not sure of where I would go and started on my way. I ended up riding various roads in the city tallying up 8.2 miles. Not bad for a 45 minute ride in the city. I am hoping to make a ride out to Battle Creek and back in a month or two. We'll see how that turns out.

296.6 lbs post ride.

Well, 7 days short of it being three years since my last post on this blog. What the hell has been going on since then? Let's take a short walk.

2008: I worked for an industrial refigeration company as a service technician. My family got another year older and I was attending school working towards my associates degree.

2009: I worked for an industrial refigeration company as a service technician. My family got another year older and took a couple more classes at the local college.

2010: I left my job at the refrigeration company to change gears a bit. I took a job offer at a local school district to be their Facilities Controls Technician. In more lay terms, I am oversee the operation of the building automation systems of their new school and the older school after it finishes going through renovations. I am also in charge of maintaining all HVAC systems within the school district.

2011: Started the year by traveling to Richmond, Virginia to visit a company called Tridium, Inc. I went through their tecnical certification on their NiagaraAx program. This program can tie in any combination of DDC programs and make them look and act as one program. I have since taken the school's building automation system from what the installation contractor set it up as and raised it to a whole new level.

This job has given me the opportunity to not only practice my skills but to study and experiment with new ideas and techniques that have not been done with this system yet. I have piqued the interests of Tridium to possibly work on packaging these concepts and programming into it's main packaging for future application revisions. We'll see where this goes. I'm excited but not allowing this to take over my priorities.

Well, that will be all for now. More to come. I promise.

When you start something new, there is only one place to begin...the beginning! So, I'm going to start this blog-site with some fundamentals. I will be putting up, periodically, information on the basics that we take for granted in everyday HVAC/R. Today is part one of a multi-step posting.

Please bear with me as I get used to writing my ideas out in a setting like this...

Psychrometrics

Psychrometrics or psychrometry are terms used to describe the field of engineering concerned with the determination of physical and thermodynamic properties of gas-vapor mixtures. In HVAC/R, we use psychrometrics with air-water mixtures.

Atmospheric air contains water vapor, pollutants, and gases, such as nitrogen, oxygen, carbon dioxide, etc.

Dry air is referred to as air devoid of water vapor and pollutants.

Moist air a mixture of dry air and water vapor...this is the basis for psychrometric analysis.

A solid understanding of the physical and thermal properties of moist air is the foundation for conceptual and design analysis of heating, cooling and industrial processes. The list or terms below are off the top of my head...if I mistyped or flat-out am off the mark...feel free to let me know.

Common terms used in Psychrometrics:

Absolute pressure is psig + 14.72 to display actual pressure not atmospheric.

Absolute humidity is the actual moisture in the air measured in grains of moisture per pound of dry air.

Sensible Heat is btuh affected by temperature (heat or cold), on a psychro chart moving left to right.

Latent Heat is btuh, affected my moisture in air (humidity), on a psychro chart moving up and down.

Sensible heat ratio is the relationship between sensible heat and latent heat. (SH%/LH%)

Dry bulb temperature is true temperature of moist air, as observed using a thermometer or temperature sensor.

Wet bulb temperature is temperature of evaporation based on the relative humidity of given sample of air. It is observed with a sling psychrometer, thermometer with a 'wet sock' or electronic measuring device.

Saturation pressure is pressure at which moist air starts boiling, at a given temperature. Layman's - point where air is at 100% relative humidity @ a given pressure/temperature ratio.

Humidity ratio is the mass of water vapor per unit mass of dry air and can be derived using mole fractions of partial pressures of the constituents. Also referred to as moisture content, mixing ratio, or specific humidity.

Relative humidity is the ratio of mole fraction of water vapor in a given sample to the mole fraction of water vapor in a sample saturated at the same temperature and pressure. Can be derived using partial pressure and saturation pressure of water vapor. In layman's terms - it is the percentage of water in a given volume of air. As temperature changes, the air volume changes but the amount of water stays the same thus changing the relative ratio...

Specific volume is the volume per unit mass of dry air. Layman's - The amount of space 1 pound of air occupies. (Cu. ft. per lbs. of dry air)

Specific heat amount of heat needed to raise a substance 1deg. of heat

Grains of moisture unit of measure to measure specific humidity or absolute humidity. (1 pound of water = 7005 grains of water)

BTU/air is measured in Btuh/pounds of air.

BTU/water is measured in Btuh/pounds of water sometimes recalculated to gallons for process measurements.

Dew-point temperature is the temperature at which a mixture becomes saturated when it is cooled at a constant pressure and constant humidity ratio. In layman's terms - the temperature at which moisture condenses.

Enthalpy is the total energy content of moist air. Sum of the enthalpies of dry air and water vapor.
Enthalpy is measured in Btuh per pound of air.
Formulas to calculate enthalpies are:
Enthalpy sensible: Qs = CFM X 1.08 X temperature difference
Enthalpy latent: Ql = CFM X 0.68 X grains difference
Enthalpy total (s+l): Qt* = CFM X 4.45 X enthalpy difference

*Qt can be better calculated by adding Qs and Ql. The Qt formula rarely comes out close due to a few factors such as rounding of enthalpy numbers, manual measurement on a chart, human error...

Adiabatic saturation temperature is the temperature at which moist air can be brought to saturation adiabatically (i.e., no heat gain or loss to the surroundings) by the evaporation of water.

Well, that is it for today. You will find this area of study either blissfully exciting or total drudgery! I am currently looking for a good chart to put up...I will have to dig through my stacks of stuff. It may take a day or two! ;)

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