heat pump

(noun)

A device that transfers heat from something at a lower temperature to something at a higher temperature by doing work.

Related Terms

Examples of heat pump in the following topics:

  • Heat Pumps and Refrigerators

    • A heat pump is a device that transfers heat energy from a heat source to a heat sink against a temperature gradient.
    • Heat pumps, air conditioners, and refrigerators utilize heat transfer from cold to hot.
    • Actually, a heat pump can be used both to heat and cool a space.
    • We define a heat pump's coefficient of performance (COPhp) to be
    • As with heat pumps, work input is required for heat transfer from cold to hot.

  • Thermal Pollution

    • As we learned in our Atom on "Heat Engines", all heat engines require heat transfer, achieved by providing (and maintaining) temperature difference between engine's heat source and heat sink.
    • Water, with its high heat capacity, works extremely well as a coolant.
    • Some may assume that by cooling the heated water, we can possibly fix the issue of thermal pollution.
    • However, as we noted in our previous Atom on "Heat Pumps and Refrigerators", work required for the additional cooling leads to more heat exhaust into the environment.

  • Work

    • Heat transfer, a less organized process, is driven by temperature differences.
    • Nevertheless, heat and work can produce identical results.
    • Both heat and work can cause a temperature increase.
    • Heat transfer into a system, such as when the Sun warms the air in a bicycle tire, can increase its temperature, and so can work done on the system, as when the bicyclist pumps air into the tire.
    • Internal energy is a form of energy completely different from either heat or work.

  • Convection

    • The specific heat of air is a weighted average of the specific heats of nitrogen and oxygen, which is c=cp≅1000 J/kg⋅C (note that the specific heat at constant pressure must be used for this process).
    • Instead heat diffusion in solids is called heat conduction, which we've just reviewed.
    • An example of convection is a car engine kept cool by the flow of water in the cooling system, with the water pump maintaining a flow of cool water to the pistons.
    • Heat is removed from the ocean when water evaporates.
    • If the water vapor condenses in liquid droplets as clouds form, heat is released in the atmosphere (this heat release is latent heat)  .

  • Specific Heat

    • The specific heat is an intensive property that describes how much heat must be added to a particular substance to raise its temperature.
    • The heat capacity is an extensive property that describes how much heat energy it takes to raise the temperature of a given system.
    • This quantity is known as the specific heat capacity (or simply, the specific heat), which is the heat capacity per unit mass of a material .
    • The specific heat is the amount of heat necessary to change the temperature of 1.00 kg of mass by 1.00ºC.
    • Note that the total heat capacity C is simply the product of the specific heat capacity c and the mass of the substance m, i.e.,

  • Overview of Heat

    • Energy can exist in many forms and heat is one of the most intriguing.
    • This module defines and explores heat transfer, its effects, and the methods by which heat is transferred.
    • Maxwell outlined four stipulations for the definition of heat:
    • After defining and quantifying heat transfer and its effects on physical systems, we will discuss the methods by which heat is transferred.
    • So many processes involve heat transfer, so that it is hard to imagine a situation where no heat transfer occurs.

  • Heat Engines

    • In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work.
    • In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work .
    • We define the efficiency of a heat engine (Eff) to be its net work output W divided by heat transfer to the engine Qh:
    • (b) A heat engine, represented here by a circle, uses part of the heat transfer to do work.
    • Qh is the heat transfer out of the hot reservoir, W is the work output, and Qc is the heat transfer into the cold reservoir.

  • Heat as Energy Transfer

    • Heat is the spontaneous transfer of energy due to a temperature difference.
    • This observation leads to the following definition of heat: Heat is the spontaneous transfer of energy due to a temperature difference .
    • Heat is often confused with temperature.
    • Heat is a form of energy, whereas temperature is not.
    • We use the phrase "heat transfer" to emphasize its nature.

  • Global Warming Revisited

    • As an engine operates, heat flows from a heat tank of greater temperature to a heat sink of lesser temperature.
    • In between these states, the heat flow is turned into useful energy with the help of heat engines.
    • Department of Energy, 70% to 72% of heat produced by burning fuel is heat lost by the engine.
    • The excess heat lost by the engine is then released into the heat sink, which in the case of many modern engines would be the Earth's atmosphere.
    • As more heat is dumped into the environment, Earth's atmospheric (or heat sink) temperature will increase.

  • Pumps and the Heart

    • The heart pumps blood through the body by contracting and relaxing, increasing and decreasing the pressure.
    • Two atria at the top of the heart receive blood and two ventricles at the bottom of the heart pump blood out of the heart.
    • A complete cardiac cycle is one round of the heart pumping blood and consists of two parts: systole (contraction of the heart muscle) and diastole (relaxation of the heart muscle).