The TLC is a compact general purpose liquid chiller. The TLC is a compact liquid chiller including reservoir, pump, and several controller options. The TLC offers the highest capacity in a benchtop unit, best control and the largest selection of pumps.
Thermoelectric Technology The Peltier Effect: Thermoelectric cooling, is a solid-state method of heat transfer through dissimilar semiconductor materials. Like their conventional refrigeration counterparts, thermoelectric cooling systems obey the basic laws of thermodynamics. However, the actual system for cooling is different. In a conventional refrigeration system, the main working parts are the evaporator, condenser, and compressor. The evaporator surface is where the liquid refrigerant boils, changes to vapor, and absorbs heat energy.
The compressor circulates the refrigerant and applies enough pressure to increase the temperature of the refrigerant above ambient level. The condenser helps discharge the absorbed heat into surrounding room air. The three main working parts in a thermoelectric refrigeration system are a cold junction, a heat sink, and a DC power source.
Two dissimilar conductors replace the refrigerant in both liquid and vapor form. The cold sink evaporator surface becomes cold through absorption of energy by the electrons as they pass from one semiconductor to another, instead of energy absorption by the refrigerant as it changes from liquid to vapor. The DC power source pumps the electrons from one semiconductor to another, and the heat sink condenser discharges the accumulated heat energy from the system.
Therefore, the thermoelectric cooling system refrigerates without refrigerant and without the use of mechanical devices, except perhaps in the auxiliary sense. The semiconductor materials used in thermoelectric cooling are N and P type, named because they either have more electrons than necessary to complete a perfect molecular lattice structure N-type or not enough electrons P-type.
Good thermoelectric semiconductor materials such as Bismuth Telluride greatly impede conventional heat conduction from hot to cold areas, yet provide an easy flow for the carriers.
If a voltage Vin is applied to terminals Tl and T2 an electrical current I will flow in the circuit. As a result of the current flow, a slight cooling effect Qc will occur at thermocouple junction A where heat is absorbed and a heating effect Qh will occur at junction B where heat is expelled.
Note that this effect may be reversed whereby a change in the direction of electric current flow will reverse the direction of heat flow. The Peltier effect can be expressed mathematically as:. Joule heating, having a magnitude of I x R where R is the electrical resistance , also occurs in the conductors as a result of current flow. This Joule heating effect acts in opposition to the Peltier effect and causes a net reduction of the available cooling.
Whether heat is absorbed or expelled depends upon the direction of both the electric current and temperature gradient. This phenomenon, known as the Thomson Effect, is of interest in respect to the principles involved but plays a negligible role in the operation of practical thermoelectric modules.
For this reason, it is ignored. Thermoelectric coolers offer a myriad of benefits when traditional cooling methods are unsuited. Additionally, thermoelectric coolers are environmentally safer than other cooling units in the market. Some benefits of using thermoelectric cooling in electronic devices include:. Additionally, coolers can dramatically improve customer electronic systems in the following problem areas:.
Application 1 Thermocyclers One application of Thermocyclers is in aerospace and defense technologies. Thermocyclers amplify segments of DNA by systematically raising and lowering the temperature of a block that holds the PCR reaction mixture.
The hot end is outside, where it disperses heat into the air. Metals are good conductors of heat, and heat naturally flows from a hotter place to a colder place. This tendency works against the thermoelectric cooler. As the Peltier effect sucks the heat to one end, the conductivity of the metal tries to draw the heat back toward the cool end.
That is why each end is attached to a heat sink. The heat sink on the outside has metal fins, to help conduct waste heat off into the air.
0コメント