python-hvac

A Python library for HVAC engineering:

• cooling and heating load calculations of buildings
• estimation of energy needs and energy consumption
• design and analysis of air and hydronic distribution systems
• air conditioning process calculations
• simulation and analysis of heat exchangers (limited for now to plain fin-and-tube heat exchangers)
• simulation and analysis of single-stage vapor compression machines and VRF systems
• sizing of refrigerant piping
• correlations for convection heat transfer coefficients and friction factors

Example scripts and notebooks can be found under docs/examples. More examples will be added over time.

Note

This project replaces the older project HVAC, which is no longer under development and will be no longer maintained.

Overview

At this moment the following subpackages are part of hvac:

air_conditioning
A package about air-conditioning processes and systems that can be used to design and analyze single-zone or multi-zone CAV and VAV air conditioning systems.

air_diffusion
A package about supplying air to a room. Implements free air jets and some procedures for designing air supply to a room which come from Awbi, H. B. (2003). VENTILATION OF BUILDINGS. Taylor & Francis. Chapter 6.

cooling_load_calc
A package for doing cooling load calculations of a building, based upon ASHRAE's Radiant-Times-Series (RTS) method. It uses a lumped capacitance model to take the thermal inertia of flat, opaque building components and the interior thermal mass of a zone into account.

sun
This package is about solar radiation on surfaces. It implements a number of sky-models (isotropic, anisotropic Perez, anisotropic HDKR, KT) to estimate the solar radiation incident on exterior surfaces. It can generate solar radiation data based on the clear-sky model or it can use TMY-data of a certain geographic location . Subpackage sun implements the equations in chapters 1 and 2 of Duffie, J. A., Beckman, W. A., & Blair, N. (2020). SOLAR ENGINEERING OF THERMAL PROCESSES, PHOTOVOLTAICS AND WIND. John Wiley & Sons.

heating_load_calc
A package for doing the heating load calculation of a building based on the method of European standard EN 12831-1 (July 2017).

energy_estimation
Estimation of the energy consumption of a building using the bin table method.

fluid_flow
A package about fluid flow in pipes and ducts and for designing and analyzing pipe and duct network systems. It includes a large number of fittings taken from Crane's TECHNICAL PAPER NO. 410M and SMACNA's HVAC SYSTEMS DUCT DESIGN MANUAL.

refrigerant_piping
Package for sizing refrigerant lines (suction line, discharge line, and liquid line) between an outdoor unit and indoor unit of an air conditioning system.

heat_transfer
This package implements a number of correlations for calculating convection heat transfer coefficients and friction factors for different geometries. Most correlations were taken from Nellis G. F. , & Klein S. A.  (2021). INTRODUCTION TO ENGINEERING HEAT TRANSFER. Cambridge University Press.

heat_exchanger
Contains two subpackages: recuperator and regenerator.

Subpackage recuperator is about heat exchangers in which the hot and cold fluid are separated by a heat transfer wall. It implements the effectiveness-NTU method for both dry and wet air cooling/heating coils. It contains (at this moment) some models of continuous fin-tube heat exchangers (air condenser, air evaporator, air-to-water cooling coil) for analysis and simulation. Implementations are based on solving methods described in Shah, R. K. , & Sekulic, D. P.  (2003). FUNDAMENTALS OF HEAT EXCHANGER DESIGN. John Wiley & Sons.

Subpackage regenerator implements the effectiveness-NTU method for a counterflow rotary regenerator (e.g. a sensible heat recovery wheel) as outlined in Shah, R. K. , & Sekulic, D. P.  (2003). FUNDAMENTALS OF HEAT EXCHANGER DESIGN. John Wiley & Sons, Chapter 5: Thermal Design Theory for Regenerators.

vapor_compression
Contains models to represent fixed- and variable speed compressors, and a model of a single-stage vapor compression machine, that integrates the models for the air evaporator and condenser in subpackage heat_exchanger. Purpose of this module is to simulate the steady-state performance of a single-stage vapor compression machine (air conditioning machine, heat pump). Several application examples have been included in the folder vapor_compression of docs/examples.

vrf_system
This subpackage can be used to model a VRF-system in relation to the building in which it is installed, with the purpose to estimate its energy consumption during a typical heating or cooling season. An example of such an energy consumption estimation and a comparison between different candidate VRF-systems in relation to the same building have been included in the folder vrf_system of docs/examples.

radiant_emitter
This subpackage implements two types of radiant heat emitters. Class PanelRadiator is for panel radiators and class RadiantFloorPanel is for floor heating panels. Both classes can be used for design and analysis.

control
This subpackage implements different types of controllers: on/off, PID, and PWM. Together with class VariableTemperatureZone in subpackage cooling_load_calc, these controller classes can be used to simulate a zone with a temperature controlled heating/cooling system. Script example_02.py in docs/examples/heating_load_calc shows an example with an on/off controller.

Besides the aforementioned application-oriented packages, hvac also includes a number of more basic subpackages which are used throughout the modules of hvac:

First of all, hvac is heavily based on third-party library pint for working with physical quantities in Python. Module pint_setup.py inside hvac does the necessary setup for using Pint's Quantity class throughout the package. When you write a script using package hvac, simply write from hvac import Quantity to work with physical quantities in your script.

Subpackage fluids contains a number of modules with classes that act like object-oriented wrappers around third-party libraries CoolProp and aipws. The principal classes of fluids, that are used extensively throughout the code, are Fluid and HumidAir, which encapsulate CoolProp's API and allow to accept Quantity objects.

Finally, subpackage charts contains a package matplotlibwrapper, being a tiny wrapper around third-party library matplotlib, meant to ease the drawing of some frequently used chart types. It also contains a module to plot refrigeration cycles on the log-p-h diagram of a refrigerant and a module to plot air conditioning processes on a psychrometric chart.