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Freeze Stat
A freeze stat is a temperature sensing device for HVAC that monitors a heat exchanger to prevent its coils from freezing. Freeze stats can be used on both refrigerant-to-air, and refrigerant-to-liquid type heat exchangers and serve different purposes with similar goals for each. Air coil The purpose of an air coil freeze stat is to keep the refrigerant-to-air heat exchanger (commonly called '' air coils'') from freezing. This kind of freeze stat is typically used for heating coils which are exposed to outside air and is usually installed on the supply air side of the coil. To accomplish this, they typically shut down the flow of outside air to a mixing box when the temperature reaches a predetermined setpoint. The setpoint for air coil freeze stats is typically about 12°C which is approximately when the dew point temperature of the air starts to drop below freezing point. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diaphragm (mechanical Device)
In mechanical engineering, mechanics, a diaphragm is a sheet of a semi-flexible material anchored at its periphery and most often round in shape. It serves either as a barrier between two chambers, moving slightly up into one chamber or down into the other depending on differences in pressure, or as a device that vibrates when certain frequencies are applied to it. A diaphragm pump uses a diaphragm to pump a fluid. A typical design is to have air on one side constantly vary in pressure, with fluid on the other side. The increase and decrease in volume caused by the action of the diaphragm alternately forces fluid out the chamber and draws more fluid in from its source. The action of the diaphragm is very similar to the action of a plunger with the exception that a diaphragm responds to changes in pressure rather than the mechanical force of the shaft. A diaphragm pressure tank is a tank which has pressurant sealed inside on one side of the diaphragm. It is favored in certain appl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Expansion Valve
A thermal expansion valve or thermostatic expansion valve (often abbreviated as TEV, TXV, or TX valve) is a component in vapor-compression refrigeration and air conditioning systems that controls the amount of refrigerant released into the evaporator and is intended to regulate the superheat of the refrigerant that flows out of the evaporator to a steady value. Although often described as a "thermostatic" valve, an expansion valve is not able to regulate the evaporator's temperature to a precise value. The evaporator's temperature will vary only with the evaporating pressure, which will have to be regulated through other means (such as by adjusting the compressor's capacity). Thermal expansion valves are often referred to generically as "metering devices", although this may also refer to any other device that releases liquid refrigerant into the low-pressure section but does not react to temperature, such as a capillary tube or a pressure-controlled valve. Theory of operation A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reversing Valve
A reversing valve is a type of valve and is a component in a heat pump, that changes the direction of refrigerant flow. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows a residence or facility to be heated and cooled by a single piece of equipment, by the same means, and with the same hardware. Operation The reversing valve has two states, relaxed (unactivated) versus energized. The energized state is typically achieved by applying 24 volts AC, which is commonly used in HVAC equipment. The heat pump can be designed by the manufacturer to produce either cooling or heating with the reversing valve in the relaxed state. When the reversing valve is energized, it will produce the opposite transfer of heat from its relaxed state. For example, a reversing valve installed in such a way as to produce cooling when relaxed will produce heating when energized. Likewise, a reversing valve installed to produce h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Exchanger
A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant. Flow arrangement Image:Heat_exc_1-1.svg, Fig. 1: Shell and tube heat exchanger, single pass (1–1 parallel f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crankcase Heater
A crankcase heater is an electrical component in a compressor in an air-conditioning system, heat pump system, or chiller system. The crankcase heater is normally on all the time, even when the unit is not running, though temperature sensors and set points may turn it off when not needed. A crankcase heater's sole purpose is to prevent refrigerant migration and mixing with crankcase oil when the unit is off, and to prevent condensation of refrigerant in the crankcase of a compressor. The crankcase heater keeps refrigerant at a temperature higher than the coldest part of the system. A crankcase heater generally has the same electrical symbol as a resistor because it converts electricity directly into heat via electrical resistance. The resistance in the heater coil determines the heat it produces when voltage is applied. Installation Some air conditioning equipment manufacturers install crankcase heaters either in the compressor (insertion type), or mount them externally aroun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcontroller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals. Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips. In modern terminology, a microcontroller is similar to, but less sophisticated than, a system on a chip (SoC). An SoC may connect the external microcontroller chips as the motherboard components, but an SoC usually integrates the advanced peripherals like graphics processing unit (GPU) and Wi-Fi interface controller as its internal microcontroller unit circuits. Microcontrollers are use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's central processing unit. The integrated circuit is capable of interpreting and executing program instructions and performing arithmetic operations. The microprocessor is a multipurpose, clock-driven, register-based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory, and provides results (also in binary form) as output. Microprocessors contain both combinational logic and sequential digital logic, and operate on numbers and symbols represented in the binary number system. The integration of a whole CPU onto a single or a few integrated circuits using Very-Large-Scale Integration (VLSI) greatly reduced the cost of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Normally Closed
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow. Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. Many specialized forms exist, such as the toggle switch, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Normally Open
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow. Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. Many specialized forms exist, such as the toggle switch, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switch
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow. Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. Many specialized forms exist, such as the toggle switch, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
