A binary vapor power cycle consists of two ideal Rankine cycles with steam and Refrigerant 134a as the working fluids. The mass flow rate of steam is 2 kg/s. In the steam cycle, superheated vapor enters the turbine at 8 MPa, 600°C, and saturated liquid exits the condenser at 250 kPa. In the interconnecting heat exchanger, energy rejected by heat transfer from the steam cycle is provided to the Refrigerant 134a cycle. The heat exchanger experiences no stray heat transfer with its surroundings. Superheated Refrigerant 134a leaves the heat exchanger at 600 kPa, 30°C, which enters the Refrigerant 134a turbine. Saturated liquid leaves the Refrigerant 134a condenser at 100 kPa. Determine (a) the net power developed by the binary cycle, in kW. (b) the rate of heat addition to the binary cycle, in kW. (c) the thermal efficiency of the binary cycle. (d) the rate of entropy production in the interconnecting heat exchanger, in kW/K.

Answer: harry styles

There are three main types of elevators commonly used: traction with a machine room, machine-room-less traction, and hydraulic; however, there are variations on each type.

Infrared sensor is most used sensor in wireless technology where remote controlling functions and detection of surrounding objects/ obstacles are involved. this post will discuss about what is infrared sensor, its working principle, how it works, types, applications, advantages and disadvantages. what is infrared sensor

ir sensor is a simple electronic device which emits and detects ir radiation in order to find out certain objects/obstacles in its range. some of its features are heat and motion sensing.

ir sensors use infrared radiation of wavelength between 0.75 to 1000µm which falls between visible and microwave regions of electromagnetic spectrum. ir region is not visible to human eyes. infrared spectrum is categorized into three regions based on its wavelength i.e. near infrared, mid infrared, far infrared.

wavelength regions of infrared spectrum

near ir – 0.75µm to 3 µm
mid ir – 3 µm to 6 µm
far ir – > 6 µm
1 introduction to infrared sensor

fig. 1 – introduction to infrared sensor

working principle of infrared sensor

infrared sensors works on three fundamental physics laws:

planck’s radiation law: any object whose temperature is not equal to absolute zero (0 kelvin) emits radiation.
stephan boltzmann law: the total energy emitted at all wavelengths by a black body is related to the absolute temperature.
wein’s displacement law: objects of different temperature emit spectra that peak at different wavelengths that is inversely proportional to temperature.
key elements of infrared detection system

the key elements of infrared detection system are:

ir transmitter

ir transmitter acts as source for ir radiation. according to plank’s radiation law, every object is a source of ir radiation at temp t above 0 kelvin. in most cases black body radiators, tungsten lamps, silicon carbide, infrared lasers, leds of infrared wavelength are used as sources.

transmission medium

as the name suggests, transmission medium provides passage for the radiation to reach from ir transmitter to ir receiver. vacuum, atmosphere and optical fibers are used as medium.

ir receiver

generally ir receivers are photo diode and photo transistors. they are capable of detecting infrared radiation. hence ir receiver is also called as ir detector. variety of receivers are available based on wavelength, voltage and package.

ir transmitter and receivers are selected with matching parameters. some of deciding specifications of receivers are photosensitivity or responsivity, noise equivalent power and detectivity.