Heat Transfer and Fluid Flow
ASHRAE Technical Committee 1.3

Scope of TC 1.3

TC 1.3 is concerned with the fundamental principles of the transport of energy, mass, and momentum, especially the study of and application to, physical processes in air conditioning, refrigeration, heating and related areas of environmental engineering.


The ASHRAE Handbook is published in a series of four volumes, one of which is revised each year, ensuring that no volume is older than four years.

The Handbook can be purchased at the ASHRAE Bookstore by clicking on this link.

TC 1.3 is responsible for the following chapters in the ASHRAE FUNDAMENTALS Volume:

Fundamentals: Fluid Flow
Flowing fluids in HVAC&R systems can transfer heat, mass, and momentum. This chapter introduces the basics of fluid mechanics related to HVAC processes, reviews pertinent flow processes, and presents a general discussion of single-phase fluid flow analysis.

Fundamentals: Heat Transfer
Heat transfer is energy transferred because of a temperature difference. Energy moves from a higher-temperature region to a lower-temperature region by one or more of three modes: conduction, radiation, and convection. This chapter presents elementary principles of single-phase heat transfer, with emphasis on HVAC applications. Boiling and condensation are discussed in Two-Phase Flow chapter. More specific information on heat transfer to or from buildings or refrigerated spaces can be found in other chapters of this volume and in a chapter on refrigerated facilities in the ASHRAE Handbook—Refrigeration. Physical properties of substances can be found in this volume and in the Thermal Properties of Food chapter of the ASHRAE Handbook—Refrigeration. Heat transfer equipment, including evaporators, condensers, heating and cooling coils, furnaces, and radiators, is covered in the  ASHRAE Handbook—HVAC Systems and Equipment.

Fundamentals: Two-Phase Flow
This chapter introduces two-phase flow and heat transfer processes of pure substances and refrigerant mixtures. Thus, some multiphase processes that are important to HVAC&R applications are not discussed here. The ASHRAE Handbook—HVAC Systems and Equipment provides information on several such applications, including humidification, particulate contaminants, cooling towers, and evaporative air cooling. See Absorption Cooling, Heating, and Refrigeration chapter of the ASHRAE Handbook—Refrigeration for information on these processes.

Fundamentals: Mass Transfer
This chapter addresses mass transfer principles and provides methods of solving a simultaneous heat and mass transfer problem involving air and water vapor, emphasizing air-conditioning processes. The formulations presented can help analyze performance of specific equipment. For discussion of performance of cooling coils, evaporative condensers, cooling towers, and air washers, see respective chapters of the ASHRAE Handbook—HVAC Systems and Equipment.

Fundamentals: Physical Properties of Materials
Values in this chapter’s tables are in consistent units to assist the engineer looking for approximate values. For data on refrigerants, see Chapter 29; for secondary coolants, see Chapter 31. Chapter 26 gives more information on the values for materials used in building construction and insulation. Many properties vary with temperature, material density, and composition. The references document the source of the values and pro-vide more detail or values for materials not listed here.

Comment on the Handbook: ASHRAE welcomes your comments on the Handbook or a specific Handbook chapter.  To submit a comment about any aspect or part of the Handbook series, you can use the Handbook Comment Form.

Review a Handbook Chapter: To provide your feedback about a specific Handbook chapter, you can answer the brief survey questions on the Handbook Chapter Review Form.


Technical committees develop and sponsor technical sessions at the winter and annual conferences. Information about their future technical program is discussed at each TC meeting and at the TC’s Program Subcommittee meeting.

ASHRAE publishes papers and transactions from presentations at its conference events. In addition, ASHRAE records most of the seminar sessions from its conferences on DVD. These DVDs are ideal for use at chapter meetings, in university courses, or company lunch and learns. Products available from the most recent conference may be found here.

At the Atlanta conference, TC 1.3 sponsored the following technical sessions:

CONFERENCE PAPER SESSION 7: Refrigerant Measurements in Micro-Enhanced Geometries
Refrigerant performance in a variety of micro-enhanced geometries continues to be investigated to improve system performance. This session examines the impact of refrigerant maldistribution on unwanted superheat regions in micro-channel heat exchangers and reports measurements on several developmental refrigerants in micro-finned geometries.

SEMINAR 29 (Intermediate): State-of-the-Art Heat Exchangers: Novel Visualization and Design Concepts
Heat transfer investigations are essential to continually develop advanced heat exchangers and HVAC&R systems. Conventional techniques provide limited insights on the performance of advanced heat exchanger designs and can be limiting in exploring the full potential of new surfaces or channel geometries. This seminar presents two innovative techniques to investigate the heat transfer and pressure drop in advanced heat exchangers. The first presentation illustrates the use of neutron imaging to visualize the two-phase flow in diabetic flow inside microchannel heat exchanger tubes. The second presentation describes development of a cost-effective and compact multipass manifold microchannel heat and mass exchanger for HVAC applications, which is less prone to the fouling and flow instability in two-phase applications and shows visualizations results of the two-phase flow in the presence of an innovative manifold design for microchannel enhanced tubes.


Technical Committees are responsible for identifying research topics, proposing research projects, selecting bidders, and monitoring research projects funded by ASHRAE. Information about their specific research program is discussed at each TC meeting and at the TC’s Research Subcommittee meeting.

TC 1.3 currently has one active project (cosponsored by TC 8.5):
1556-RP: Characterization of Liquid Refrigerant Flow Emerging from a Flooded Evaporator Tube Bundle
The primary objective of the research will be to experimentally determine the size distribution, velocity, and outflow and drop back of liquid refrigerant droplets emerging from the top of the tube bundle in a flooded evaporator. A parametric study is to be carried out to quantify the effects of surface geometry, fluid properties, and operating conditions on the droplet size distribution, velocity, and egress and regress.

TC 1.3 currently has one active RTAR:
1683 RTAR-R1:Experimental Evaluation of Two-Phase Pressure Drop and Flow Pattern in U-Bends with Ammonia

Other topics of Interest:
•Two-Phase NH3 flow through tees and u-bends.
•Low mass-flux correlations for in-tube boiling of NH3.
•Heat transfer performance of new low GWP refrigerants.
•Particle fouling for in-tube flow of CO2 sequestration equipment (M. Ohadi).
•Heat Transfer and Pressure Drop correlations of refrigerant mixtures in low-temperature applications (M. Ohadi).
•The effects of fouling on airside droplet condensation in heat exchangers (Eric Rats).
•Effect of Dust on Fouling of air side heat exchangers.
•Heat Transfer enhancement with micro encapsulated phase change materials.
•Nanofluids in HVAC.


ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry. ASHRAE publishes the following three types of voluntary consensus standards: Method of Measurement or Test (MOT), Standard Design and Standard Practice. ASHRAE does not write rating standards unless a suitable rating standard will not otherwise be available. ASHRAE is accredited by the American National Standards Institute (ANSI) and follows ANSI's requirements for due process and standards development. Standards may be purchased at the ASHRAE Bookstore.

TC 1.3 is not cognizant for any standards at this time.

Other Activities

TIP: If MTG involvement add here otherwise leave blank.

TC 1.3 participates in the following multi-disciplinary task group:

Lower Global Warming Potential Alternative Refrigerants
MTG.LowGWP is established to coordinate TC/TG/TRG technical activities to help transition the HVAC&R industry to sustainable lower Global Warming Potential (GWP) alternative refrigerants. The MTG will further request participation from US EPA and AHRI. The MTG responsibilities include suggestions for research, development and presentation of technical programs of all types on alternative lower GWP refrigerants, suggestions for Life Cycle Climate Performance (LCCP) systems evaluation for different applications, development of lower GWP solutions for different applications, and a special publication detailing aspects of LCCP applied to the HVAC&R fields. 


ASHRAE Technical FAQs are provided as a service to ASHRAE members, users of ASHRAE publications, and the general public. While every effort has been made to ensure their accuracy and reliability, they are advisory and provided for informational purposes only, and in many cases represent only one person’s view. They are not intended and should not be relied on as an official statement of ASHRAE. Technical questions not addressed may be submitted to the ASHRAE Technical Services department at tse@ashrae.net.