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Psychrosi [updated] — Thermexcel Programme

is a psychrometric calculation program developed by ThermExcel

designed to analyze and calculate the thermodynamic properties of humid air. It is primarily used by HVAC engineers for sizing air conditioning installations, swimming pool thermal calculations, and analyzing air mixture processes. ThermExcel Key Features of PsychroSI Comprehensive Property Calculation

: By inputting just two known air state elements (e.g., dry temperature and relative humidity), the program calculates all other psychrometric parameters, including: Wet-bulb and dew point temperatures. Specific moisture (humidity ratio) and enthalpy. Air density and specific volume. Sensible and latent heat values. Integrated Weather Library

: The program includes a built-in library of global weather data, which provides the standard climatic parameters required for dimensioning HVAC systems. Advanced Humidification Modeling

: It specifically calculates the state of air before and after vaporization, including autonomous steam water injection processes where temperature changes are minimal but precision is required. HVAC Process Analysis : PsychroSI can model complex air treatments, such as: Air mixture calculations. Reheating and cooling processes. Swimming pool surface evaporation and thermal requirements. ThermExcel Practical Application

For professional use, the program allows for precise state point plotting similar to a manual psychrometric chart

, but with automated accuracy for industrial and commercial building management. Penn State Extension input specific data into PsychroSI, or are you looking for a comparison with other HVAC calculation tools?

programs, sizing, piping, HVAC, heating, air ... - ThermExcel

Since these terms are highly technical (engineering software + a Greek-derived scientific term for chilling/cooling), this post is tailored for HVAC engineers, energy auditors, and cryogenic system designers.

Why "Psychrosi" is the forgotten metric

Most engineers obsess over heating. Heating is forgiving. If you oversize a radiator, the room gets warm faster—no harm done.

Cooling (Psychrosi) is unforgiving. Oversize a cooling coil? You get freezing, coil icing, and humidity control chaos. Undersize it? The space never reaches setpoint.

ThermExcel treats psychrosi with the respect it deserves. It reminds us that moving heat into a cold sink is harder than moving heat out of a hot source.

What is ThermExcel?

Before we dive into the cold, let's define the tool. ThermExcel is not a flashy, cloud-based SaaS product. It is a suite of Microsoft Excel-based engineering tools. Think of it as the Swiss Army knife for thermal and fluid calculations.

It was built for engineers who love transparency. Instead of a black box, ThermExcel shows you every formula, every coefficient, and every unit conversion. It handles:

  • Heat loss through walls.
  • Pipe sizing.
  • Psychrometrics (air properties).
  • Heat exchanger design.

And this is where psychrosi enters the chat.

The Cold Logic: Simulating "Psychrosi" with the ThermExcel Programme

By: [Your Name]

When you hear the word "psychrosi" (ψύχρωση), you might think it’s a new medical condition or a character from a fantasy novel. In reality, it’s a fascinating Greek term that simply means cooling, chilling, or the process of becoming cold.

But in the world of thermal engineering, cooling isn't simple. It’s a battle against physics. And when you need to win that battle for a building, an industrial pipe, or a heat exchanger, one tool stands out for the old guard of European engineers: ThermExcel. thermexcel programme psychrosi

Here is why the marriage of this legacy software and the concept of psychrosi still matters in a world of CFD and BIM.

Advanced Psychrosi Analysis: Freeze Protection and Reheat

One critical insight from ThermExcel simulations is that after intense psychrosi, air leaves nearly saturated at a low temperature (e.g., 12°C, 95% RH). This air cannot be supplied directly to a comfort zone because it feels drafty and clammy. Therefore, the model should include a reheat coil.

Using ThermExcel in series:

  1. Process 1-2 (Psychrosi): Cooling & dehumidification.
  2. Process 2-3 (Sensible heating): Increase dry-bulb to 20°C without changing W.

To model this:

  • After calculating State 2, set State 3 T_db3 = 20°C, W3 = W2.
  • ThermExcel function: =Psychro("Heating", T_db2, W2, T_db3)

The total energy cost is the sum of psychrosi (sensible + latent) plus reheat (sensible), which ThermExcel can compute automatically.

3. User Interface Mockup (Text)

-------------------------------------------------
| PSYCHROSI – DYNAMIC SIMULATOR v2.0           |
-------------------------------------------------
| [Psychrometric Chart Live View]               |
|    (dot moves as you change sliders)          |
|                                                 |
| Current Zone: 22.0°C DB | 50% RH | 11.1°C DP |
|                                                 |
| --- LOADS ---                                  |
| Sensible: [====|===] 2500 W                   |
| Latent:   [==|=====] 800 W                    |
| SHR = 0.76                                    |
|                                                 |
| --- COLD SURFACE CHECK ---                    |
| Wall Temp: [12.0°C]   → 🔴 CONDENSATION RISK  |
|                                                 |
| --- COIL EXIT (after cooling) ---             |
| Supply: 13.5°C DB | 12.8°C WB | 91% RH        |
| ⚠️ Fogging risk: ΔT = 0.7°C (critical)        |
-------------------------------------------------

5. Technical Implementation (For Developer)

  • Engine: Use standard psychrometric formulas (ASHRAE Fundamentals – Hyland & Wexler).
  • Integration: Pull inputs from existing ThermExcel sheets (coil, mixing, loads).
  • Output: Export a time-step CSV (if extended to 24h simulation) or a single PDF report titled “Psychrosi Risk Assessment.”

program by ThermExcel is an Excel-based tool designed for HVAC engineers to perform complex psychrometric calculations for moist air. It is particularly useful for sizing heating, ventilation, and air conditioning systems, as well as specialized applications like indoor swimming pools. 1. Key Functions of PsychroSI

The software allows you to determine all physical properties of moist air based on two known input variables. Common input combinations include: Dry Bulb Temperature Relative Humidity Dry Bulb Temperature Wet Bulb Temperature Dry Bulb Temperature Specific Humidity Specific Humidity 2. Core Capabilities Air Mixture Calculations

: Analyze the resulting properties of two air streams mixing (e.g., fresh outdoor air and recirculated indoor air). Cooling and Dehumidification

: Calculate the heat exchange and moisture removal during cooling processes. Heating and Humidification : Determine energy requirements for air treatment. Swimming Pool Thermal Analysis : A dedicated module specifically for the thermal calculation of indoor pools

, including water evaporation rates and required ventilation to maintain comfort. 3. User Interface & Data Management According to the official documentation , PsychroSI features: Custom Toolbar

: A dedicated ribbon or menu in Excel for quick access to calculation boxes and macros. Modular Worksheets

: You can create separate files for different projects or duplicate sheets within the same file to compare similar design scenarios. Detailed Results

: Outputs include density, dew point, vapor pressure, and specific volume. 4. Practical Workflow Define Ambient Conditions

: Enter the altitude or atmospheric pressure of the project location. Input States

: Define the "State of Air" (Point 1, Point 2, etc.) using the known variables. Process Simulation

: Select the transformation type (e.g., sensible heating, cooling with condensation). Review Heat Loads

: The program will generate the total, sensible, and latent heat changes (in kW or Watts). Why "Psychrosi" is the forgotten metric Most engineers

For more specific pipe sizing or steam distribution, you might also look into complementary tools like ThermoVapor or HydroTherm module or the air mixing

program by ThermExcel is a specialized psychrometric calculation software designed for analyzing humid air states and HVAC processes. It serves as a digital alternative to manual psychrometric charts, allowing for precise determination of air properties and thermal calculations. ThermExcel Core Capabilities

The software calculates various humid air parameters based on two input elements. Key outputs and features include: ThermExcel Air Property Calculations

: Dry and wet bulb temperature, relative humidity, dew point, specific moisture, enthalpy, density, and vapor pressure. HVAC Process Analysis

: Psychrometric calculations for air mixing, as well as reheating or cooling processes. Specialised Thermal Calculations

: Specifically includes modules for swimming pool thermal calculations. Energy Metrics

: Determines sensible and latent heat, as well as the enthalpy of the air. ThermExcel Software Versions

The ThermExcel PsychroSI programme is a specialized Excel-based software tool designed for HVAC engineers, researchers, and building designers to perform precise psychrometric calculations. The name "PsychroSI" is derived from psychrometrics (the study of moist air properties) and SI (International System of Units), though the software is often available in versions supporting US units as well. Core Functionality of PsychroSI

The primary utility of the PsychroSI programme is its ability to determine the complete state of humid air based on just two input parameters. By entering any two known variables, the software uses iterative algorithms to calculate all other related thermodynamic properties. Common input pairs include:

Dry Temperature combined with Relative Humidity, Wet Bulb Temperature, Specific Moisture, or Enthalpy. Relative Humidity and Specific Moisture. Specific Moisture and Enthalpy.

The programme maintains a high degree of precision, typically with a margin of error of no more than 0.1°C for temperature calculations. Key Modules and Advanced Calculations

Beyond basic point-state calculations, the PsychroSI suite includes specialized modules for complex HVAC processes:

Air Mixture and Heat Exchange: The software can calculate the resulting state of air when two different streams are mixed, or when air is subjected to reheating or cooling.

Adiabatic Processes: It models cooling through water spraying (evaporative cooling), where the air reaches saturation without external heat exchange.

Swimming Pool Thermal Sizing: A dedicated module for swimming pool calculations allows users to determine the thermal requirements for maintaining pool environments, including evaporation rates and necessary air treatment.

Weather Data Integration: The programme includes an integrated library of meteorological data for over 265 sites, allowing for accurate dimensioning based on local climate conditions. User Interface and Integration

ThermExcel's PsychroSI is built as an Excel-based tool, making it highly accessible for professionals already using spreadsheets for engineering. Heat loss through walls

Custom Toolbars: It features a dedicated command bar for quick access to calculation boxes and macros.

Multi-Sheet Support: Users can manage multiple studies within a single file by duplicating worksheets for different scenarios.

Automated Data Storage: The software creates separate work files to optimize data management and storage. Typical Applications ThermExcel Présentation du programme PsychroSI - ThermExcel

The PsychroSI programme from ThermExcel is a specialized calculation tool for HVAC professionals designed to analyze and calculate the properties of humid air based on inputting two known variables. It handles air mixtures, isothermal humidification, and swimming pool environments while providing custom, project-specific, and SI-compliant data management. Detailed technical resources and documentation can be found on ThermExcel's website

programs, sizing, piping, HVAC, heating, air ... - ThermExcel

Unlocking the Secrets of Air Conditioning and Ventilation: The Power of ThermExcel and Psychrometry

As engineers and architects strive to create more comfortable, efficient, and sustainable buildings, the importance of accurate calculations and analysis in air conditioning and ventilation systems cannot be overstated. One crucial tool in achieving this goal is ThermExcel, a software program that has revolutionized the way professionals approach psychrometry and HVAC design. In this article, we'll explore the capabilities of ThermExcel and the fundamental principles of psychrometry, highlighting their combined impact on the built environment.

What is Psychrometry?

Psychrometry is the study of the physical and thermodynamic properties of gas-vapor mixtures, particularly air and water vapor. This complex relationship is crucial in understanding the behavior of air in various environments, from residential and commercial buildings to industrial and agricultural settings. Psychrometry helps engineers and technicians determine the optimum conditions for heating, cooling, humidifying, and dehumidifying air to achieve thermal comfort, prevent moisture-related issues, and maintain indoor air quality.

The ThermExcel Program

ThermExcel is a comprehensive software tool designed to simplify psychrometric calculations and analysis. This intuitive program allows users to easily compute and visualize various psychrometric properties, such as:

  1. Air properties: temperature, humidity ratio, relative humidity, enthalpy, and specific volume.
  2. Psychrometric charts: generate custom charts to visualize the relationships between air properties.
  3. HVAC system design: size and analyze heating, cooling, humidifying, and dehumidifying systems.
  4. Moisture condensation and evaporation: assess the risk of condensation and evaporation in various applications.

Key Features and Benefits

ThermExcel's robust features and benefits include:

  1. Accurate calculations: based on the latest psychrometric charts and equations, ensuring reliable results.
  2. User-friendly interface: easy data input and output, with customizable units and formats.
  3. Comprehensive analysis: evaluate various HVAC system configurations and psychrometric processes.
  4. Time-saving: rapidly perform complex calculations and generate detailed reports.
  5. Improved design: optimize HVAC system performance, energy efficiency, and indoor air quality.

Real-World Applications

The combined power of ThermExcel and psychrometry has far-reaching implications in various industries, including:

  1. Building design and operation: optimize HVAC systems for energy efficiency, comfort, and indoor air quality.
  2. Industrial processes: control humidity and temperature in manufacturing, storage, and logistics applications.
  3. Agriculture and horticulture: maintain optimal growing conditions for crops and livestock.
  4. Museums and archives: preserve sensitive artifacts and documents by controlling temperature and humidity.

Conclusion

The ThermExcel program, built on the principles of psychrometry, has revolutionized the way professionals approach HVAC design, analysis, and optimization. By accurately calculating and visualizing psychrometric properties, engineers and architects can create more comfortable, efficient, and sustainable buildings, while minimizing the risk of moisture-related issues and energy waste. As the demand for high-performance buildings continues to grow, the importance of ThermExcel and psychrometry will only continue to rise.

D. Mixed Air - No Spreadsheet Guesswork

  • Instead of manual mixing formulas, this feature provides a triangle mixer:
    • Point 1: Outside air (user sets DB/WB)
    • Point 2: Return air (user sets DB/WB)
    • Slider: % OA (0% to 100%)
  • Psychrosi computes: Mixed DB, WB, RH, h, w, and dew point.
  • Auto-warning: If mixed point is below freezing (coil frost risk) or above 90% RH (duct mold risk).

7. Comparison with Other Software

| Feature | Thermexcel | CoilDesigner (U. Illinois) | EVAP-COND (NIST) | |---------|------------|----------------------------|------------------| | Psychrometric model | Yes (full) | Yes | Partial | | Dehumidification | Yes | Yes | No | | Frost modeling | Basic | Advanced | No | | User interface | GUI + wizard | GUI + script | GUI | | Industry standard in Europe | High | Medium | Low (refrigeration) |

Thermexcel is preferred for European HVAC manufacturers due to CETIAT’s certification and correlations based on European fin geometries.

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