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Cold Store Energy Flow Analyser

A typical HFC cold store with electric defrost wastes over 90% of input electricity on compressor losses, condenser rejection, and defrost heating. This interactive Sankey diagram shows exactly where every kilowatt goes across four refrigeration scenarios.

Compare HFC R404A (electric and hot gas defrost), ammonia R717, and the Karnot iCOOL CO₂ transcritical system with FLX Flex Defrost delivering 4.2 EER with free hot water recovery.

Energy Flow Diagram

HFC R404A + Electric Defrost
HFC R404A + Hot Gas Defrost
Ammonia R717
Karnot iCOOL CO₂ + FLX
EER: 0.9

FLX Flex Defrost — Technical Detail

Charge Mode

  • CO₂ subcooling charges PCM at 4.5 kWh/hr
  • Coconut oil + graphene composite PCM
  • Passively charged — no extra electricity
  • Continuous charge during normal cooling cycle

Discharge Mode (iSAVE)

  • iSAVE opens valve to release stored thermal energy
  • 8.1 kg ice formed in 8 minutes
  • Zero electrical draw during defrost
  • Product temperature deviation < 0.5°C

Super-Boost Mode

  • Hot discharge gas at 80–90°C routed direct to FLX
  • 4.5 kW thermal boost capacity
  • For heavy frost build-up conditions
  • Ambient >40°C tropical environments
Patent Pending PCT/WO2022069581A1 — Licensed to Karnot Energy Solutions Inc.

Adjust Parameters

Cost Comparison

Cold Room Specification

Energy & Refrigerant Costs

Your Current System

Monthly electricity--
Annual defrost cost--
Annual refrigerant top-up--
Annual CO₂e (Scope 1)--
Total annual cost--

With Karnot iCOOL + FLX + Hot Water

Monthly electricity--
Annual defrost cost--
Hot water savings--
Annual refrigerant (CO₂)--
Annual CO₂e (Scope 1)--
Total annual cost--
Annual Saving
--
PHP
CO₂e Avoided
--
tonnes/year
5-Year Saving
--
PHP
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System Comparison

Metric HFC Electric Defrost HFC Hot Gas Defrost Ammonia R717 iCOOL + FLX
Effective EER0.92.63.7 (clean)14.2
Defrost Energy CostVery HighModerateLowZero
Free Hot WaterNoNoPossible2Yes (CIP 75°C)
Refrigerant GWP3,9223,92201
PFAS / Forever ChemicalYesYesNoNo
Safety ClassificationStandard (A1)Standard (A1)Specialist (B2L)3Standard (A1)
NCG Buildup RiskYesYesHigh4None
Kigali Phase-Down RiskHighHighNoneNone
Scope 1 Emissions----0 t--
Refrigerant Cost / kg₱1,400₱1,400₱180₱50

1 Ammonia EER of 3.7 assumes clean system with zero NCG. With typical 8% NCG buildup, effective EER drops to ~3.0. 2 Ammonia desuperheating heat recovery requires additional equipment and specialist pipework. 3 Ammonia is toxic above 25 ppm and flammable at 15–28% concentration in air; requires gas detection, emergency ventilation, and trained operators. 4 NCG (Non-Condensable Gas) from air ingress or oil breakdown accumulates in ammonia condensers, reducing heat transfer and increasing head pressure.

Frequently Asked Questions

Why does electric defrost waste so much energy in cold stores?
Electric defrost uses resistance heaters mounted on evaporator coils, typically drawing 8 kW per coil across 10 coils for 20-30 minutes per cycle. With 4-6 defrost cycles per day, this adds significant heat directly into the cold room that the compressor must then remove. The effective EER (Energy Efficiency Ratio) drops from the compressor's nominal 2.6 to as low as 0.9 when defrost energy is accounted for. This is the single largest hidden cost in many cold store operations.
What does the Kigali Amendment mean for R404A cold stores?
The Kigali Amendment to the Montreal Protocol mandates an 80-85% phase-down of HFC production globally by 2047. R404A, with a GWP of 3,922, is a primary target. Operators face rising refrigerant costs as supply tightens, potential equipment obsolescence, increasing insurance premiums, and regulatory compliance costs. R404A is also a PFAS (per- and polyfluoroalkyl substance) - a "forever chemical" facing additional regulatory pressure under EU and US PFAS restrictions.
Is CO₂ refrigeration suitable for tropical climates like the Philippines?
Yes. Transcritical CO₂ systems are specifically designed for high ambient temperatures. While traditional subcritical CO₂ systems lose efficiency above 25°C, transcritical operation maintains high performance even at 45°C ambient. The Karnot iCOOL system achieves an EER of 4.2 in tropical conditions by recovering the high-grade waste heat (80-90°C) for hot water, effectively turning a thermodynamic challenge into a free energy benefit.
How does FLX Flex Defrost achieve zero electrical draw?
The FLX system uses Phase Change Material (PCM) made from coconut oil and graphene composite that is passively charged by CO₂ subcooling during normal cooling operation. When defrost is needed, the iSAVE controller opens a valve to release stored thermal energy directly to the evaporator coils. This produces 8.1 kg of ice in 8 minutes with zero additional electrical draw, keeping product temperature deviation below 0.5°C throughout the defrost cycle.

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See exactly how much your cold store could save by switching to Karnot iCOOL CO₂ + FLX. We provide a detailed engineering report with payback analysis, emissions reduction, and implementation timeline.

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