Introduction Maxim 100 Maxim 200 Maxim 300 Maxim 400

MAXIM 400

Maxim 400 is a PC-based Refrigeration Plant Simulator with the following main features:

Simulation of two types of Refrigeration Systems:

• Direct Refrigeration
  
• Secondary (Brine) Refrigeration
  
• Refrigeration systems are represented in the form of colored, interactive flow diagrams.
• Plant, equipment and valves are shown graphically along with critical values of Temperature, Pressure, Flow etc.
• Students are expected to set up and run the refrigeration plant using mouse point & click methods.
• Realistic, interactive images of critical plant such as TEV valves, thermostats and controllers are provided.
• The plant will react convincingly to any sequence of events - either correct or incorrect.
• A variety of start (initial) conditions can be set-up and stored.
• Dynamic plots of Enthalpy / Pressure
• Heat gains through composite wall are adjustable
• Variety of Refrigerant gases modeled.
• Alarm System with adjustable set points
• Simulated faults can be entered by the instructor

Direct Expansion System

The direct expansion refrigerant system is circulated by an electric motor driven reciprocating compressor fitted with suction and discharge valves. Suction and discharge pressures for the compressor are calculated and displayed together with their equivalent temperatures.

The water-cooled condenser is of the shell and tube type with isolating valves on the inlet and outlet side of both the gas and water circulation circuits.

A separate liquid receiver is provided after the condenser together with its appropriate isolating, drain and relief valves.

There are three cold chambers maintained at different temperatures. Fan assisted circulation is used in the two cold chambers to improve and accelerate the cooling rate.

Heat gains through the walls of the rooms are calculated on inside temperatures and an ambient (but variable) outside temperature.

Each of the chambers is supplied through a thermostatically operated expansion valve (TEV), the individual TEVs being appropriately matched to the temperature level of a particular room. Back-pressure valves are also fitted to the outlet from each room. Room thermostats trip solenoid valves to close the flow through to particular rooms.

An Electrically heated defrosting system is fitted to the two cold rooms.

The overall refrigerant capacity is monitored and, in the event of leakage occurring, the system may be topped up or charged through either of the two charging points.

The compressor will shut-down on:

• Low gas pressure
• High temperature
• Low oil pressure

Brine System

The Brine System has a simple refrigeration cycle serving a single flooded evaporator.

The Brine itself or Secondary Refrigerant is circulated round the chambers via the brine pump that draws from the flooded evaporator and discharges into a manifold.

A header tank maintains a positive head on the system and makes up for any leakage that may occur.

A mixing tank allows control of the Brine density. This can be adjusted according to the expected lowest running temperature.

Defrost is available by using the brine heater.

Three-way valves regulate the room temperature. They control the amount of flow around the room cooling coils, or by pass it to the return manifold as the case may be. Buttons on the three way valves allow the set point to be adjusted.

Heat gain through walls is adjustable and displayed interactively.

The direct expansion system control panel		The direct expansion refrigeration system simulated by Maxim 400
Dynamic pressure enthalpy plot		The secondary (brine) refrigeration system simulated by Maxim 400