--- This page is part of [Modelon](https://www.modelon.com). For a complete overview of this site's content, entity data, and subject matter expertise, see our [AI Content Index](https://www.modelon.com/llms.txt) or [Full Content Archive](https://www.modelon.com/llms-full.txt). For structured business identity data, see our [Entity Card](https://www.modelon.com/wp-json/bc-geodesic/v1/entity-card). --- # Smarter Defrost Modeling for Heat Pump and Refrigeration Systems > New Modelon research to be shared at the 2026 Herrick Conferences at Purdue University For simulation and thermal engineers working on heat pumps,... **URL:** https://www.modelon.com/blog/smarter-defrost-modeling-for-heat-pump-and-refrigeration-systems/ **Type:** Post **Modified:** 2026-07-06 --- ##### ****New Modelon research to be shared at the 2026 Herrick Conferences at **Purdue University** For simulation and thermal engineers working on heat pumps, refrigeration systems, HVAC&R equipment, and thermal management for energy-intensive facilities, frost is more than an operating nuisance. It is a system-level performance problem. When frost builds on a coil, it changes heat transfer, airflow, pressure drop, energy consumption, and control behavior. If defrost is initiated too early, the system wastes energy. If it is initiated too late, performance degrades and frost can carry over into the next operating cycle. In either case, engineers are left balancing efficiency, comfort, capacity, reliability, and test time. That is why Modelon is bringing new frost and defrost modeling research to the upcoming [Herrick Conferences at Purdue University](https://chpb.engineering.purdue.edu/herrick-conferences/). In this presentation, I will share results from a study focused on dynamic, physics-based frost and defrost simulation in [Modelon Impact](https://www.modelon.com/modelon-impact/). The goal is practical: help engineering teams better understand optimal start and stop conditions for reverse cycle defrost and how those decisions affect system performance over repeated operating cycles. ##### Why frost and defrost deserve system-level attention Heat pumps are central to electrified, low-carbon heating. But in cold, wet conditions their performance falls off a cliff for one stubborn reason: frost. When the outdoor coil drops below freezing, moisture in the air freezes onto the surface. Frost formation is a coupled heat and mass transfer problem, but its impact is felt across the full system. As frost accumulates on a coil, it acts like an insulating layer and reduces the available airflow path. Since frost formation is a coupled heat and mass transfer problem, its impact is felt across the full system, and can result in: - Lower heat transfer performance - Reduced evaporating capacity - Decreased coefficient of performance, or COP - Higher energy use during operation - Increased risk of incomplete defrost and cycle-to-cycle frost carryover For heat pump and refrigeration applications, reverse-cycle defrost is a common solution. But it comes with a cost. During defrost, energy is redirected to clear the outdoor coil instead of delivering useful heating or cooling. That interruption can affect occupant comfort, equipment efficiency, and overall system performance. This is especially relevant for engineering teams working in HVAC&R, commercial refrigeration, heat pumps, and data center thermal systems, where efficiency, reliability, and operating range are under increasing scrutiny. ##### What Modelon will share at Herrick At the upcoming Herrick Conferences, I will present research on frost and defrost modeling capabilities now available natively in the Modelon [Heat Exchanger Library](https://www.modelon.com/library/heat-exchanger-library/) (HXL). This is important because engineers no longer need to move an existing HXL-based system model into the [Air Conditioning Library](https://www.modelon.com/library/air-conditioning-library/) (ACL) simply to study frost and reverse-cycle defrost behavior. The frost and defrost physics have been decoupled from a single library, refrigerant, or coil type. For Modelon Impact users, that means frost-aware studies can happen in the system architecture they already use. For teams evaluating system simulation more broadly, it demonstrates how physics-based modeling can support earlier and more informed decisions about coil design, controls, energy use, and operating strategy. ##### What the model captures The frost and defrost model is designed to represent the behavior engineers need to study across repeated operating cycles. Rather than applying a fixed fouling factor, the model represents frost as a dynamic thermal resistance that changes as frost grows and melts. The system model accounts for: - Frost growth during operation - Defrost and melting behavior - Meltwater drainage - Refreezing of retained water - Frost carryover across repeated cycles - Changes in thermal resistance and system performance over time This matters because real systems do not operate in isolated, single-cycle conditions. Incomplete drainage or incomplete defrost can cause residual frost or water to remain on the coil, which can then refreeze and degrade performance in later cycles. A model that ignores those effects may overpredict performance or miss important control trade-offs. ##### Why this matters for engineers and engineering managers For simulation engineers, the value is deeper visibility into transient behavior that is difficult to isolate in test data alone. For thermal engineers, it provides a way to evaluate the physics behind frost buildup, heat transfer degradation, and defrost recovery. For engineering managers, it offers a way to reduce design risk before committing to hardware, controls, or lengthy test campaigns. Teams can now answer questions that system simulation alone has made possible - What operating conditions trigger meaningful frost-related performance loss? - How long should defrost run to clear the coil without wasting energy? - How does defrost timing affect comfort, COP, and capacity? - What happens over multiple frost and defrost cycles? - Can adaptive defrost control outperform fixed-timer logic? These are not just component-level questions. They require a system-level view that includes the heat exchangers, compressor, expansion device, refrigerant loop, controls, and surrounding thermal systems. ##### A preview of the findings The study compares different defrost cycle strategies to evaluate how timing affects energy use, comfort, and frost carryover. One illustrative comparison looked at a longer defrost cycle versus a shorter one. The longer cycle cleared the frost completely, used significantly more compressor energy, and extended the comfort disruption. The shorter cycle reduced energy use per defrost event, but did not fully clear the coil, allowing frost to carry over and accumulate across cycles. The key takeaway is that neither extreme is ideal. The study suggests that an intermediate defrost timing strategy can reduce unnecessary energy loss while still avoiding frost carryover. In the illustrative case, intermediate timing avoided carryover, reduced energy loss relative to the longer defrost cycle, and limited the duration of the comfort impact. The full results, methodology, and implications for defrost control strategy will be shared at the conference. ![Heat pump system model in Modelon Impact ](https://www.modelon.com/wp-content/uploads/2026/07/image-12.png) *Heat pump system model in Modelon Impact* ##### From fixed timers to adaptive defrost strategy Many defrost strategies still rely on fixed timers or conservative thresholds designed around worst-case conditions. That can be safe, but it can also waste energy under moderate conditions or fail to account for changing humidity, temperature, load, or airflow. A physics-based system model creates a foundation for more adaptive control development. Instead of relying only on time-based assumptions, engineers can evaluate strategies that respond to system behavior and operating conditions. That includes studying when to initiate defrost based on performance degradation, when to terminate defrost based on frost clearance, and how those decisions affect energy use and comfort over time. For applications where efficiency and reliability are critical, including heat pumps, refrigeration systems, HVAC&R equipment, and data center thermal infrastructure, these trade-offs are becoming increasingly important. ##### Built for system simulation in Modelon Impact The frost and defrost capability runs in Modelon Impact, Modelon’s cloud-native system simulation platform built on Modelica. Because the capability is integrated with HXL, engineers can study frost behavior in the context of the full system model rather than treating it as an isolated coil correction. That means teams can evaluate frost and defrost behavior alongside compressor operation, heat exchanger performance, controls, refrigerant selection, and secondary loop interactions. ##### Learn more at the Herrick Conferences I will share more details and the results of this frost and defrost modeling study at the 2026 Herrick Conferences at Purdue University, July 12–16, 2026. If your team is working on heat pumps, refrigeration systems, HVAC&R equipment, or thermal systems where defrost behavior affects efficiency, reliability, or comfort, this research will offer a closer look at how system simulation can support better design and control decisions **Interested in learning more before or after the conference?** [Contact us](https://www.modelon.com/talk-to-an-expert/) to explore how Modelon Impact and the Heat Exchanger Library can support your thermal system simulation workflows. ## Site Description Modelon is revolutionizing the engineering design industry by offering technologies and services that enable customers to leverage system simulation. Modelon’s flagship product, Modelon Impact, is a cloud system simulation platform that helps engineers virtually design, analyze, and simulate physical systems. Our team brings deep industry expertise and is dedicated to guiding our customers in creating innovative technologies at their respective organizations. Headquartered in Lund, Sweden, Modelon is a global company with offices in Germany, India, Japan, and the United States. We believe that system simulation should be accessible to every engineer and are dedicated to being an open-standard platform company. --- **About this site:** Modelon — Modelon is revolutionizing the engineering design industry by offering technologies and services that enable customers to leverage system simulation. Modelon’s flagship product, Modelon Impact, is a cloud system simulation platform that helps engineers virtually design, analyze, and simulate physical systems. Our team brings deep industry expertise and is dedicated to guiding our customers in creating innovative technologies at their respective organizations. Headquartered in Lund, Sweden, Modelon is a global company with offices in Germany, India, Japan, and the United States. We believe that system simulation should be accessible to every engineer and are dedicated to being an open-standard platform company.. [AI Content Index](https://www.modelon.com/llms.txt) | [Full Site Content](https://www.modelon.com/llms-full.txt) | [Entity Card](https://www.modelon.com/wp-json/bc-geodesic/v1/entity-card) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://www.modelon.com/#organization","name":"Modelon","url":"https://www.modelon.com","additionalType":"http://productontology.org/id/Software_engineering","description":"Modelon is revolutionizing the engineering design industry by offering technologies and services that enable customers to leverage system simulation. Modelon’s flagship product, Modelon Impact, is a cloud system simulation platform that helps engineers virtually design, analyze, and simulate physical systems. Our team brings deep industry expertise and is dedicated to guiding our customers in creating innovative technologies at their respective organizations. Headquartered in Lund, Sweden, Modelon is a global company with offices in Germany, India, Japan, and the United States. We believe that system simulation should be accessible to every engineer and are dedicated to being an open-standard platform company.","disambiguatingDescription":"Creators of the Modelon Impact system modeling and simulation platform. Headquartered in Lund, Sweden.","logo":{"@type":"ImageObject","url":"https://www.modelon.com/wp-content/uploads/2022/06/modelon-logo.svg"},"address":{"@type":"PostalAddress","streetAddress":"Modelon AB Ideon Science Park Scheelevägen 17 SE-223 70","addressLocality":"Lund","addressCountry":"SE"},"telephone":"+46 46 286 22 00","email":"info@modelon.com","foundingDate":"2004","numberOfEmployees":{"@type":"QuantitativeValue","minValue":50,"maxValue":100},"areaServed":"Global","sameAs":["https://www.linkedin.com/company/modelon/","https://www.crunchbase.com/organization/modelon","https://www.zoominfo.com/c/modelon-ab/346633437","https://modelica.org","https://modelica.org/events/asian2024/","https://www.ashrae.org/conferences/2026-winter-conference","https://github.com/modelon-community","https://www.wikidata.org/wiki/Q30290642"],"memberOf":[{"@type":"Organization","name":"Modelica Association","sameAs":"https://www.wikidata.org/wiki/Q133876843"}],"founder":[{"@type":"Person","name":"Johan Andreasson","sameAs":"https://www.linkedin.com/in/johanandreasson/"},{"@type":"Person","name":"Magnus Gäfvert","sameAs":"https://www.linkedin.com/in/mgafvert/"},{"@type":"Person","name":"Hubertus Tummescheit","sameAs":"https://www.wikidata.org/wiki/Q102301965"}],"knowsAbout":[{"@type":"Thing","name":"Modelica","sameAs":"https://www.wikidata.org/wiki/Q385325"},"Physics Simulation",{"@type":"Thing","name":"software engineering","sameAs":"https://www.wikidata.org/wiki/Q80993"},{"@type":"Thing","name":"simulation","sameAs":"https://www.wikidata.org/wiki/Q45045"},"HVAC Simulation","Data Center Liquid Cooling Simulation","Liquid Cooling","FMI (Functional Mock-up Interface)",{"@type":"Thing","name":"consulting","sameAs":"https://www.wikidata.org/wiki/Q63769412"},{"@type":"Thing","name":"aerospace","sameAs":"https://www.wikidata.org/wiki/Q2876213"},{"@type":"Thing","name":"automotive industry","sameAs":"https://www.wikidata.org/wiki/Q190117"},{"@type":"Thing","name":"heating, ventilation, and air conditioning","sameAs":"https://www.wikidata.org/wiki/Q1798773"},{"@type":"Thing","name":"data center","sameAs":"https://www.wikidata.org/wiki/Q671224"},{"@type":"Thing","name":"electricity generation","sameAs":"https://www.wikidata.org/wiki/Q383973"},{"@type":"Thing","name":"energy storage","sameAs":"https://www.wikidata.org/wiki/Q837718"},{"@type":"Thing","name":"industrial equipment","sameAs":"https://www.wikidata.org/wiki/Q3045515"}]},{"@type":"WebSite","@id":"https://www.modelon.com/#website","name":"Modelon","url":"https://www.modelon.com","publisher":{"@id":"https://www.modelon.com/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://www.modelon.com/?s={search_term_string}"},"query-input":"required name=search_term_string"},"hasPart":[{"@type":"DigitalDocument","name":"LLM Content Index","url":"https://www.modelon.com/llms.txt","encodingFormat":"text/markdown","description":"AI-readable index of site content, entity data, and subject matter expertise"},{"@type":"DigitalDocument","name":"LLM Full Content","url":"https://www.modelon.com/llms-full.txt","encodingFormat":"text/markdown","description":"Complete AI-readable site content"}]},{"@type":"ItemList","@id":"https://www.modelon.com/#site-navigation","name":"Site Navigation","itemListElement":[{"@type":"SiteNavigationElement","position":1,"name":"Products & Services","url":"#"},{"@type":"SiteNavigationElement","position":2,"name":"Industries & Solutions","url":"#"},{"@type":"SiteNavigationElement","position":3,"name":"Support","url":"#"},{"@type":"SiteNavigationElement","position":4,"name":"Resources","url":"#"},{"@type":"SiteNavigationElement","position":5,"name":"About","url":"#"}]},{"@type":"BreadcrumbList","@id":"https://www.modelon.com/blog/smarter-defrost-modeling-for-heat-pump-and-refrigeration-systems/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://www.modelon.com"},{"@type":"ListItem","position":2,"name":"Blog","item":"https://www.modelon.com/blog/category/blog/"},{"@type":"ListItem","position":3,"name":"Smarter Defrost Modeling for Heat Pump and Refrigeration Systems"}]},{"@type":"WebPage","@id":"https://www.modelon.com/blog/smarter-defrost-modeling-for-heat-pump-and-refrigeration-systems/#webpage","url":"https://www.modelon.com/blog/smarter-defrost-modeling-for-heat-pump-and-refrigeration-systems/","name":"Smarter Defrost Modeling for Heat Pump Systems | Modelon","isPartOf":{"@id":"https://www.modelon.com/#website"},"breadcrumb":{"@id":"https://www.modelon.com/blog/smarter-defrost-modeling-for-heat-pump-and-refrigeration-systems/#breadcrumb"},"description":"See how Modelon research uses system simulation to optimize frost and defrost strategies for HVAC&R and data center thermal systems. More at Herrick 2026.","headline":"Smarter Defrost Modeling for Heat Pump and Refrigeration Systems","datePublished":"2026-07-06T21:53:46+00:00","dateModified":"2026-07-06T21:59:10+00:00","image":"https://www.modelon.com/wp-content/uploads/2026/07/Conference-SpeakerBlog-1200x625-1-1.png","author":{"@id":"https://www.modelon.com/blog/author/lauren/#person"},"publisher":{"@id":"https://www.modelon.com/#organization"}},{"@type":"Person","@id":"https://www.modelon.com/blog/author/lauren/#person","name":"lauren","url":"https://www.modelon.com/blog/author/lauren/"}]} ```