ZHX Combined Flow Evaporative Condenser

Detailed Overview of HACST ZHX Combined Flow Evaporative Condenser

Evaporative condensers, such as the HACST ZHX combined flow model, are specialized heat rejection devices widely used in industries requiring efficient refrigeration and cooling, such as energy, chemical, pharmaceutical, food processing, and industrial refrigeration. Unlike closed circuit cooling towers (e.g., BNX series), which cool a process fluid in a closed loop, evaporative condensers directly condense a refrigerant (e.g., ammonia or Freon) from a gas to a liquid by rejecting heat to the atmosphere. The ZHX model combines advanced design features to optimize performance, reduce resource consumption, and minimize environmental impact.

1. Applications of Evaporative Condensers

The ZHX evaporative condenser is versatile and serves a wide range of industries and applications, as outlined:

• Food Industry:
  • Poultry Slaughtering Plant: Cools refrigeration systems for meat processing and preservation.
  • Multi-purpose Cold Storage: Maintains low temperatures for perishable goods.
  • Beer and Beverage Industry: Supports refrigeration in brewing and bottling processes.
  • Industrial Ice/Skating Rink: Produces ice for recreational or industrial use.
  • Ice Cream Factory: Ensures consistent cooling for production and storage.
  • Fish Processing Industry: Maintains cold chain integrity for seafood.
• Chemical and Pharmaceutical Industry:
  • Inter-cooling of Methanol/Methanol Synthetic Ammonia Compressor: Cools compressors in chemical synthesis processes.
  • Syngas Cooling Condensation: Condenses synthesis gas in chemical plants.
  • Methanol Distillation Process Cooling Condensation: Supports distillation by condensing vapors.
  • Gas Cooling of Natural Gas or Coke Gas Exchange Process: Cools gases during processing.
  • Purification Process Cooling Condensation: Facilitates purification by condensing vapors.
  • Steam Condensation of Turbine, Ethyl Acetate Condensation: Condenses steam or chemical vapors in industrial processes.
• Other Industries:
  • Energy and Coal: Cools equipment in power generation and coal processing.
  • Industrial Refrigeration: Supports large-scale refrigeration systems.
  • Building Air Conditioning: Provides cooling for HVAC systems in commercial buildings.
  • Cold Storage: Maintains low temperatures for warehouses.

2. Working Principle of ZHX Combined Flow Evaporative Condenser

The ZHX model operates on a combined flow principle, integrating parallel air and water paths with a combination of condensing coils and PVC fill to maximize heat transfer. Here’s a detailed explanation of its operation:

• Refrigerant Flow:
  • The hot, gaseous refrigerant (e.g., ammonia or Freon) enters the condensing coil, where it releases heat and condenses into a liquid.
  • The coil is fully soaked by spraying water, which enhances heat transfer through evaporative cooling.
• Water and Air Interaction:
  • Spraying Water: Water is sprayed over the coil, absorbing heat from the refrigerant. As the water evaporates, it removes heat via the latent heat of vaporization.
  • Air Flow: Fresh air is drawn into the condenser (typically by axial fans) and flows in the same direction as the water (parallel flow), passing over the coil and through PVC fill.
  • Heat Transfer: The heat from the refrigerant is transferred through the coil wall to the water and air. The water evaporates, forming a saturated wet-hot vapor that is discharged into the atmosphere by the fan.
  • PVC Fill: The PVC fill increases the contact time and surface area between water and air, cooling the spray water primarily through sensible heat conduction (direct heat transfer without phase change). This reduces the water temperature before it is recirculated.
• Water Recirculation:
  • A drift eliminator captures water droplets from the exiting air stream, minimizing water loss.
  • The collected water is directed to a water basin at the base of the condenser for recycled spraying.
  • The sloped water basin design facilitates cleaning and prevents sediment buildup.
• Low Water Consumption:
  • The efficient use of evaporative cooling and drift eliminators ensures minimal water loss, making the ZHX model suitable for water-scarce regions.

3. Advantages of HACST ZHX Evaporative Condenser

The ZHX model offers significant advantages over traditional condensers (e.g., air-cooled, shell-and-tube, or atmospheric condensers), as highlighted below:

1. Energy Saving:
   • Lower Condensing Temperature: The evaporative condenser achieves condensing temperatures closer to the wet bulb temperature (e.g., 5–10°C lower than air-cooled condensers). For every 1°C increase in condensing temperature, power consumption rises by 3–3.5%. Thus, the ZHX model reduces energy use significantly.
   • Efficient Heat Transfer: The combination of evaporative cooling and PVC fill maximizes heat rejection, reducing the energy required for refrigeration.
2. Water Conservation:
   • Latent Heat Utilization: The ZHX model leverages the latent heat of water vaporization, requiring less water than traditional cooling systems.
   • Drift Eliminators: Minimize water loss, typically achieving drift rates of 0.001–0.002% of the circulating water flow.
   • Recirculation: Recycled spray water reduces overall water consumption, critical in water-scarce regions.
3. Compact Structure and Low Investment Cost:
   • Integrated Design: Combines the functions of a condensing coil and cooling tower into a single unit, eliminating the need for a separate cooling tower.
   • Small Footprint: Requires less space than air-cooled or shell-and-tube condensers, ideal for facilities with spatial constraints.
   • Reduced Components: Lower coil heat exchange area, fewer fans, and reduced motor power consumption decrease material and operational costs.
   • Lower Installation Costs: Simplified piping and system design reduce upfront investment.
4. Environmental-Friendly:
   • Reduced Ammonia Loss: Unlike traditional shell-and-tube or atmospheric condensers, which may vent non-condensable gases containing up to 90% ammonia, the ZHX model minimizes ammonia emissions, reducing environmental pollution and material loss.
   • Lower Environmental Impact: Efficient water and energy use aligns with sustainability goals.
5. Excellent Heat Exchange Performance:
   • Parallel Air and Water Paths: Ensures uniform water distribution, avoiding dry spots and scale formation on the coil.
   • PVC Fill: Enhances heat transfer by cooling the spray water, improving overall efficiency.
   • Scale Prevention: The continuous water flow and fill design minimize scaling, maintaining performance over time.
6. Convenient Maintenance:
   • Accessible Design: The large maintenance space allows technicians to inspect and service the unit during operation.
   • Suspended PVC Fill: Facilitates cleaning and replacement.
   • Sloped Water Basin: Prevents sediment accumulation, simplifying basin maintenance.
7. Convenient Transportation and Installation:
   • Modular Design: The ZHX model is shipped in standard upper and bottom body parts, reducing transportation costs and simplifying assembly.
   • Ease of Installation: Pre-assembled components and compact design streamline on-site setup.

4. Comparison with Traditional Condensers

The ZHX evaporative condenser outperforms traditional condenser types in several areas:

• Vs. Air-Cooled Condensers:
  • Advantage: Lower condensing temperatures (5–10°C closer to wet bulb) reduce compressor energy consumption by 15–25%.
  • Space: Smaller footprint due to evaporative cooling’s higher efficiency.
  • Maintenance: Less prone to fouling than air-cooled units in dusty environments.
• Vs. Shell-and-Tube Condensers:
  • Advantage: Eliminates the need for a separate cooling tower, reducing system complexity and footprint.
  • Environmental: Prevents ammonia venting, unlike shell-and-tube systems that may release non-condensable gases.
  • Efficiency: Evaporative cooling provides better heat transfer than water-cooled shell-and-tube systems.
• Vs. Atmospheric Condensers:
  • Advantage: More compact and efficient, with lower water and energy consumption.
  • Environmental: Reduces ammonia emissions, addressing pollution concerns.

5. Selection Process for Evaporative Condensers

The provided selection process ensures the ZHX evaporative condenser meets the system’s heat rejection requirements. Here’s a detailed explanation of the steps, with the ammonia refrigeration example clarified:

1. Determine Total System Heat Load:
   • Calculate the total heat to be rejected, including:
     • Latent Heat of Vaporization: Heat released as the refrigerant condenses.
     • Sensible Heat: Heat from cooling the refrigerant or other media.
   • For ammonia refrigeration: Total heat = Compressor refrigerating capacity + Compressor shaft power.
   • Example: Total exhaust heat = 1200 kW.
2. Determine Design Conditions:
   • Specify key parameters:
     • Condensing Temperature (Tc): The temperature at which the refrigerant condenses (e.g., 36°C).
     • Wet Bulb Temperature (Twb): The ambient wet bulb temperature (e.g., 28°C).
     • Inlet/Outlet Temperatures: If applicable, for the refrigerant or cooling medium.
3. Check Correction Coefficient:
   • Use a manufacturer-provided graph or table to determine the correction coefficient based on condensing and wet bulb temperatures.
   • Example: For Tc = 36°C and Twb = 28°C, the correction coefficient is 1.35 (from Graph 1).
4. Calculate Corrected Heat Load:
   • Multiply the total heat load by the correction coefficient to account for operating conditions.
   • Example: 1200 kW × 1.35 = 1620 kW (corrected heat load).
5. Select the Evaporative Condenser:
   • Choose a model with a heat rejection capacity equal to or greater than the corrected heat load.
   • Example: Select ZHX-1765, with a heat rejection capacity > 1620 kW.

Additional Notes:

• The nominal heat rejection in manufacturer datasheets is typically based on standard conditions (e.g., Tc = 37°C, Twb = 26°C).
• The running weight includes the equipment, refrigerant, and water in the basin.
• Custom designs can be manufactured for specific requirements.

6. Comparison with BNX Closed Circuit Cooling Tower

Since your previous query discussed the BNX counterflow closed circuit cooling tower, it’s useful to clarify the differences between evaporative condensers (ZHX) and closed circuit cooling towers (BNX):

• Purpose:
  • ZHX Evaporative Condenser: Directly condenses a refrigerant (e.g., ammonia) from gas to liquid, used in refrigeration systems.
  • BNX Closed Circuit Cooling Tower: Cools a process fluid (e.g., water, glycol) in a closed loop, used for general process cooling.
• Design:
  • ZHX: Uses a condensing coil and PVC fill, with parallel air and water flow. The refrigerant flows inside the coil, and water evaporates to reject heat.
  • BNX: Uses a coil with no fill media, with counterflow air and water. The process fluid remains in a closed loop, isolated from the spray water.
• Applications:
  • ZHX: Primarily for refrigeration (e.g., cold storage, food processing, chemical plants).
  • BNX: Broader applications (e.g., data centers, HVAC, industrial processes).
• Water and Energy Efficiency:
  • Both are water- and energy-efficient compared to air-cooled systems, but the ZHX’s PVC fill enhances heat transfer for refrigeration, while the BNX’s no-fill design maximizes coil area for process cooling.
• Maintenance:
  • ZHX: Requires maintenance of PVC fill and water treatment for spray water.
  • BNX: Lower maintenance due to no fill media, but still requires water treatment.

7. Potential Specifications (Generalized)

While specific ZHX-1765 specifications depend on the manufacturer, typical characteristics for combined flow evaporative condensers include:

• Heat Rejection Capacity: 500 kW to 5 MW, depending on model.
• Refrigerant: Ammonia, Freon (R134a, R410A), or others.
• Flow Rates:
  • Spray water: 50–1000 m³/h, recirculated.
  • Air: 10,000–500,000 m³/h.
• Fan Power: 5–75 kW, often with variable-frequency drives (VFDs).
• Materials:
  • Coils: Stainless steel or galvanized steel for corrosion resistance.
  • Casing: Fiberglass-reinforced plastic (FRP) or stainless steel.
  • Fill: PVC for durability and heat transfer.
• Drift Loss: ≤0.002% of circulating water flow.
• Footprint: 3–15 m² per MW of cooling capacity.
• Noise Levels: 60–85 dB(A) at 10 meters, with low-noise options.

Note: Consult the manufacturer’s datasheet for precise ZHX-1765 specifications.

8. Environmental and Economic Benefits

• Environmental:
  • Reduces ammonia emissions, addressing pollution concerns in chemical plants.
  • Saves water through efficient evaporation and drift eliminators.
  • Lowers energy consumption, reducing greenhouse gas emissions.
• Economic:
  • Lower Operating Costs: Reduced energy and water use, plus minimal maintenance.
  • Lower Capital Costs: Compact design and integrated functionality reduce installation expenses.
  • Longevity: Durable materials and scale-resistant design extend equipment life.

9. Limitations and Considerations

• Initial Cost: Higher upfront cost than air-cooled condensers, though offset by long-term savings.
• Water Treatment: Spray water requires treatment to prevent scaling or biological growth.
• Climate Dependence: Optimal in humid climates; performance may decrease in very dry conditions.
• Refrigerant Handling: Requires proper management of refrigerants like ammonia due to safety and environmental concerns.

10. Conclusion

The HACST ZHX combined flow evaporative condenser is a highly efficient, compact, and environmentally friendly solution for refrigeration-intensive industries, including food processing, chemical manufacturing, and cold storage. Its parallel air and water paths, PVC fill, and integrated design provide superior heat transfer, energy savings, and water conservation compared to traditional condensers. The detailed selection process ensures accurate sizing for specific applications, as demonstrated in the ammonia refrigeration example. Compared to the BNX closed circuit cooling tower, the ZHX model is specialized for refrigerant condensation, making it ideal for refrigeration systems rather than general process cooling.