Heat transfer

Thermotronics » Heat transfer

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction or diffusion, thermal convection, thermal radiation and transfer of energy by phase changes. Conduction is heat transfer by means of molecular agitation within a material without any motion of the material as a whole. Convection is a heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it. Thermal radiation is energy transfer by the emission of electromagnetic waves which carry energy away from the emitting object. When a substance changes from one state, or phase, of matter to another we say that it has undergone a change of state or phase (for example, ice melts and becomes water, water evaporates and becomes water vapor); these changes of phase always occur with a change of heat. Heat, which is energy, either comes into the material during a change of phase or heat comes out of the material during this change. Heat transfer principles may be used to preserve, increase or decrease temperature in a wide variety of circumstances and heat transfer methods are used in numerous disciplines, such as automotive engineering, thermal management of electronic devices and systems, materials processing, insulation, climate control and power station engineering. A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. There are many different types of heat exchanger available and the main are: Shell and tube, plate, tubular and air-cooled. De Lorenzo provides for this filed different trainers, such as heat transfer unit by natural or forced convection using heating elements with different geometric surfaces and supplied with data acquisition system and computer, a power supply unit for heat exchangers complete with an electronic control system and computer and a wide variety to choose accessories as plate, shell and tube, tubular or jacketed vessel with stirrer and coil heat exchangers, a water cooling tower unit to demonstrate the most widespread cooling method in industry supplied always with an electronic control system and computer with software for monitoring and heat transfer unit in concentric tubes composed of water pump, sensors, regulation valves, flow meter and touch screen computer. They are recommended for professional institutes, vocational schools and technical colleges.

Products Details

HEAT TRANSFER BY NATURAL AND FORCED CONVECTION

The DL DKT032s module is a desktop equipment that is designed for the study of heat transfer by natural or forced convection.
The system operation involves the passing air through a duct heated using heating elements with different geometric surfaces. In order to allow the study of forced convection, the system is supplied with a suitable.
The equipment includes also a computer.
TRAINING OBJECTIVES
• Study of heat dissipation by natural convection.
• Study of heat dissipation by forced convection.
• Comparison of different heat transfer rates among different sink models.
• Heat transfer parameter calculation:
- Efficiency.
- Heat transfer coefficient.
- Dissipated energy (or heat transfer).
• Calculation of the Reynolds and Nusselt number.
TECHNICAL DATA
• Convection tower section: 120x120mm.
• Convection tower length: 1 m.
• Air velocity with forced ventilation: 3 m/s (computer controlled)
• Heating elements power: 170W
• Double security system for heaters protection.
• Three heaters are supplied with the following forms:
- Heater tube bundle.
- Plate to plate heater.
- Vertical fins heater.
• A surface temperature sensor is supplied to measure the temperature in different parts of the heaters.
• The equipment is supplied with an electronic acquisition data and computer.

DL DKT032S

POWER SUPPLY FOR HEAT EXCHANGERS

This unit represents the main element of the whole heat exchange system.
With this module, it is possible to provide hot and cold water to heat exchangers.
It is also possible to measure temperatures and flow rates in each element.
All the connections used in this equipment are self‐ sealant type, quick couplings allow a fast and simple change of different exchangers avoiding possible losses of fluid.
The connections of hot and cold water are different to avoid a wrong connection.
TRAINING OBJECTIVES
• Heat transfer demonstration.
• Comparison between different types of heat exchangers.
• Comparison of results between converge‐current flows and counter‐current flows.
• Transfer coefficient measurement and effects of flow rate and temperature differential measurement.
• Calculation of energy balances and efficiency.
TECHNICAL DESCRIPTION
The module has a hot‐water tank with a capacity of 4.5 liters, with an electronic controller of temperature and level.
An electromechanical valve fills in the tank automatically when necessary.
The system water storage is protected against overheating, low water level and tank overflow.
The pumping system has a bypass that can facilitate the operating of the pump and can allow a better stabilization of the conditions in the tank.
TECHNICAL DATA
• Computer controllable heater from 0 to 1.5kW
• Peripheral pump:
Maximum flow: 10l/min (5M WC)
Power consumption: 180W
• Hot water circuit with bypass
• Maximum hot water temperature: 70°C
• Maximum hot water flow rate: 5l/min
• The unit is supplied with computer and an electronic control system.
• Dimensions: 730x1100x530 mm

DL DKC011

PLATE HEAT EXCHANGER

TECHNICAL DESCRIPTION
In the plate heat exchanger, hot and cold flows pass through alternating chambers usually thin in depth, separated at their largest surface, producing heat transfer.
The advantage of this type of heat exchanger is the compact size, and therefore, its suitable use in small spaces.
The supplied plates have a geometry that creates turbulence in the fluid, improving heat transfer.
TRAINING OBJECTIVES
• Balance of energies in the heat exchanger.
• Calculating the logarithmic average temperature difference.
• Determination of the overall transmission heat coefficient.
• Calculation of effectiveness.
TECHNICAL DATA
• Dimensions: 440x250x150mm
• Number of plates: 20
• Heat transfer surface: 0,25 m²

DL DKC012

SHELL AND TUBE HEAT EXCHANGER

TECHNICAL DESCRIPTION
The shell and tube heat exchanger is one of the most used type in industry.
In this exchanger, the cold fluid passes through a number of parallel tubes and the hot fluid goes through a chamber containing the small cold tubes, thus producing heat transfer.
The advantage of this type of heat exchanger is the compact design and the possibility to work at higher pressures than other types.
This exchanger can operate with current or countercurrent flows.
TRAINING OBJECTIVES
• Balance of energies in the heat exchanger.
• Calculating the logarithmic average temperature difference.
• Determination of the overall transmission heat coefficient.
• Calculation of effectiveness.
TECHNICAL DATA
• Dimensions: 440x250x110 mm
• Number of plates: 7
• Heat transfer surface: 0,021 m²

DL DKC013

TUBULAR HEAT EXCHANGER

TECHNICAL DESCRIPTION
The heat exchanger with concentric tubes is the simplest type.
Its advantage is the easy design.
The module has two parallel tubes through which cold fluid flows; inside these tubes there is a smaller tube through which the hot fluid flows.
The exchanger is made in two halves and it has thermocouples at the midpoints.
The learning process is very trouble‐free thanks to the possibility to clearly see the temperature variation throughout the exchanger.
This exchanger can operate with current or countercurrent flows.
TRAINING OBJECTIVES
• Balance of energies in the heat exchanger.
• Calculating the logarithmic average temperature difference.
• Determination of the overall transmission heat coefficient.
• Calculation of effectiveness.
TECHNICAL DATA
• Dimensions: 440x250x100 mm
• Number of plates: 2
• Heat transfer surface: 0,0186 m²

DL DKC014

JACKETED VESSEL WITH STIRRER AND COIL HEAT EXCHANGER

TECHNICAL DESCRIPTION
This type of heat exchanger is commonly used in the process and chemical industries, when a well defined fluid temperature is required.
The exchanger can operate with a double wall vessel or a coiled tube; the module can also operate with a continuous flow in the vessel or heating a defined quantity of a liquid.
The exchanger includes a thermocouple that continuously measures the fluid temperature within the vessel and it includes also a variable‐speed stirrer to test the effects in heat exchanger.
TRAINING OBJECTIVES
• Balance of energies in the heat exchanger.
• Calculating the logarithmic mean temperature difference.
• Determination of the overall transmission heat coefficient.
• Calculation of effectiveness.
TECHNICAL DATA
• Dimensions: 440x250x430 mm
• Vessel inner volume: 1.840 cm³
• Serpentine length: 290 cm
• Heat transfer surface (vessel‐coil): 0.044 m²
• Vessel outer volume: 1.691,5 cm³
• Heat transfer surface between inner and outer vessel: 0,0899 m²

DL DKC015

WATER COOLING TOWER

The trainer is designed to demonstrate the most widespread cooling method in industry.
The demonstrated method shows the cooling of hot water to room temperature.
Air at room temperature is introduced by a fan from the lower part of the system at the bottom of the tower.
While hot water is sprayed in the upper section of the tower, hot water cools down until it reaches room temperature, then it is reheated and the process starts again.
The unit is supplied with a personal computer.
TRAINING OBJECTIVES
• Thermodynamic fundamentals of cooling tower • Measuring the air flow, air and water temperatures and of humidity
• Changes of state of the air in a h-x chart
• Determination of the cooling capacity
• Energy balances
• Calculation of process parameters such as cooling distance limit, width of the cooling zone, etc.
TECHNICAL DATA
• Cross section: 150x150 mm.
• Air flow measurement by calibrated orifice Ø80mm.
• Three steps adjustable heater: 0,5kW, 1kW and 1.5kW.
• Maximum hot water temperature: 60°C.
• Centrifugal fan:
- Power consumption: 90W.
- Maximum air flow: 510m3 /h.
• Peripheral pump:
- Maximum flow: 10 l/min (5m M WC)
- Power consumption: 180W.
• Hot water circuit with bypass.
• Electronic regulation of the hot water flow and airflow through the computer system.
• The unit is supplied with an electronic control system with visualization and a computer system with software.

DL DKC021

HEAT TRANSFER IN CONCENTRIC TUBES

The system can show the working of a concentric tube exchanger.
The principle of the basic operation of any heat exchanger is the exchange of heat between two fluids, either because it is necessary to cool or heat some of them.
Therefore, in the exchanger there is always a hot fluid that decreases its temperature along with the same, transmitting that heat in favor of the other cold fluid in which it increases.
TRAINING OBJECTIVES
• Energy balance in the exchanger
• Determination of the heat loss that occurs towards the outside.
• Calculation of the mean temperature logarithmic difference.
• Determination of the overall coefficient of experimental heat transfer.
• Determination of the theoretical global heat transfer coefficient.
• Calculation of effectiveness
• Heat transfer in concentric tubes: parallel flow
• Heat transfer in concentric tubes: countercurrent flow
TECHNICAL DESCRIPTION
The trainer is composed of :
• Electric hot water pump
• Hot and cold sensors
• Touch screen computer
• Hot and cold water regulation valve
• Hot and cold flow meter
• Drain outlet
TECHNICAL DATA
• Pump power: 55W
• Max flow .: 300 L / h
• Lifting height: 4.5m
• Power of the resistance: 3000W
• Thermostat: 30 ... 90ºC
• Hot water tank: 20.5 l
HOT WATER CIRCUIT
• Outside diameter tube 15 mm.
• Diameter inside tube 12.4 mm.
• Tube length - heat exchange: 2 x 740mm
COLD WATER CIRCUIT
• External diameter tube 22 mm.
• Diameter inside tube 20 mm.
• Tube length - heat exchange: 2 x 740mm.

DL DKC071

Download Area

ProductsCodeCatalogueTender specsManuals SimpleVideo
HEAT TRANSFER BY NATURAL AND FORCED CONVECTIONDL DKT032S
POWER SUPPLY FOR HEAT EXCHANGERSDL DKC011
PLATE HEAT EXCHANGERDL DKC012
TUBE BUNDLE HEAT EXCHANGERDL DKC013
TUBULAR HEAT EXCHANGERDL DKC014
JACKETED VESSELDL DKC015
WATER COOLING TOWERDL DKC021
HEAT EXCHANGER CONCENTRIC TUBESDL DKC071