MODULE 2. Heat Pump Market Developments
February 9, 2026
This module examines the internal workings of electrically driven heat pumps, focusing on the thermodynamic cycle, the behavior of refrigerants, and the function of each major component in the refrigeration circuit. The objective is to gain an understanding of how heat pumps upgrade low-grade thermal energy into useful heating or cooling, and how design choices influence efficiency, reliability, and operational limits.
Lessons 1 to 3 deal with fundamental concepts:
Lesson 1 establishes the foundations. It introduces the heat pump as a thermodynamic device governed by the vapor-compression cycle, outlining the transformation of refrigerant through evaporation, compression, condensation, and expansion. The lesson presents the physical principles (temperature lift, pressure–temperature saturation relationships, and system efficiency sensitivity to source–sink temperature differences) while defining the three linked subsystems: the heat source, the refrigeration loop, and the heat distribution system.
Lesson 2 deepens the thermodynamic treatment by dissecting the vapor-compression cycle step-by-step. It distinguishes theoretical and real processes, describes component functions in situ, and examines irreversibilities arising from non-ideal compression, heat exchanger temperature differentials, and pressure losses.
Lesson 3 focuses on refrigerants as working fluids. It explains their role in heat absorption and rejection, examines key selection criteria (thermodynamic performance, safety classification, environmental impact, and material compatibility) and reviews naming conventions and current regulatory pressures driving transitions toward low-GWP alternatives.
Lessons 4 to 8 deal with the analysis of the components that make up the cycle:
Lesson 4 moves to compressors, the prime movers establishing the pressure ratio that enables phase change. It reviews types of compressors, their operating principles, and their suitability across different capacities. The discussion includes real compression behavior, lubricant requirements, refrigerant–oil compatibility, and variable-speed technologies that modulate output to reduce cycling losses and enhance seasonal efficiency.
Lesson 5 analyses external heat exchangers (evaporators and condensers) as the interfaces where heat is absorbed and rejected. It details the mechanisms of phase change, heat transfer surfaces, and design considerations related to coil geometry, materials, and environmental conditions. Special attention is given to frost formation on air-source evaporators, defrost strategies, and the influence of exchanger sizing on system stability and seasonal performance.
Lesson 6 addresses expansion devices, which regulate refrigerant mass flow and establish the pressure differential. It compares capillary tubes, thermostatic expansion valves, automatic valves, and electronic expansion valves, highlighting control strategies, superheat management, and the advantages of electronic modulation in inverter-driven systems. The lesson links valve behavior to load variation, evaporator pressure dynamics, and system protection.
Lesson 7 covers additional refrigeration-circuit components, including four-way reversing valves, solenoid and check valves, filter-driers, sight glasses, liquid receivers, and oil separators. Their roles in mode reversal, refrigerant routing, moisture and contamination mitigation, and fluid management are discussed, along with how internal leakage, pressure drops, or incorrect sizing affect COP, compressor reliability, and system response.
Lesson 8 concludes the module with ancillary components that ensure hydraulic stability, airflow management, and operational safety. It includes fans, circulating pumps, flow switches, pressure and freeze protection devices, expansion tanks, and buffer tanks.
