Defrost Cycle Improvement At Kuhlman Incorporated, we specialize in turnkey mechanical refrigeration system solutions for industrial and commercial applications. Our expert team offers a full range of services—including design, construction, installation, and servicing—to ensure our customers’ refrigeration needs are fully met. Equipped with over six decades of industry experience, we have the knowledge and skills to develop more efficient and effective systems. Below we outline how we aim to improve defrost cycle times in refrigeration systems.


Testing More Efficient Ways of Defrosting

In refrigeration systems that operate below the freezing point, ice and frost accumulation on the air cooler component can affect the overall performance of the system. Resolving this issue necessitates the integration of a defrost system. 

Ideally, a defrost system should focus 100% of the heat generated on melting the ice on the surface of the air cooler without significantly affecting the temperature of the condenser coil or the refrigerated space. While this goal is not always feasible, our team is committed to determining the most efficient and effective method of defrosting for each customer’s needs. We focus on the following factors when evaluating the viability of a method: 

  • Ice and frost removal capabilities (with minimal energy requirements)
  • Heat transference into the refrigerated space
  • Moisture transference into the refrigerated space
  • Energy usage
  • Energy loss from flash gas and non-condensed hot gas bypassing through the evaporator
  • Defrost cycle times
  • Reliability and safety


Types of Defrost Systems

Defrost systems are classified into two main categories:

  • External heat source systems: electrical defrost and water defrost
  • Internal heat source systems: hot gas defrost (including both the pressure control method and the liquid drain method)

Hot gas defrost systems use the “free energy”—i.e., heat—generated by the system to defrost the air cooler surface. In pressure control variations, a valve in the defrost drain line controls the evaporator pressure. Liquid drain variants employ a float valve that allows liquid refrigerant to drain out but blocks the flow of non-condensed hot gas. 

Findings from laboratory tests that measured the pressure, temperature, and changing mass flows caused by each type of mechanism, translate to the following conclusions:

  • Liquid drain systems drain condensate at the lowest pressure levels, while pressure control systems drain at pre-set pressure levels. 
  • Liquid drain systems ensure only the right fluids drain as the float valve blocks any flow except for liquid condensate. In contrast, the valves in pressure control systems release both liquid and gas when the hot gas capacity is too high.
  • Liquid drain systems require less hot gas for defrosting operations than pressure control systems. This quality is particularly apparent for longer defrost cycles. 

Based on the above information and our extensive knowledge of the design, construction, and installation of mechanical refrigeration systems in general, we create custom solutions for our customers that are both effective and efficient. 


Contact the Refrigeration Solution Experts at Kuhlman Inc. Today

At Kuhlman Inc., we are dedicated to ensuring every customer receives the right refrigeration system for their needs. To learn more about our refrigeration system capabilities, contact us today