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Plate Heat exchanger

Plate Heat exchanger A sandwich of plastic or metal plates with interlaced air paths.  Heat is transferred between airstreams from one side of the plate to  the other.  The plates are typically spaced at 4 to 6mm apart.  Can also be used to recover coolth. Heat recovery efficiency up to 70%. With a plate heat exchanger, heat cuts through the surface and separates the hot medium from the cold. Thus, heating and cooling fluids and gases use minimal energy levels. The theory of heat transfer between mediums and fluids happens when Heat is always transferred from a hot medium to a cold medium. There must always be a temperature difference between the mediums. The heat lost from the hot medium is equal to the amount of heat gained by the cold medium. Advantages of plate heat exchanger Improved temperature approach, true counter-current flow, 80-90% less hold-up volume. Low capital investment, installation costs, limited maintenance and operating costs. Less fouling, stress, wear, and corros

Air Handling Unit (AHU)

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Air Handling Unit (AHU) An air handler, or air handling unit (AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning  (HVAC) system.  An air handler is usually a large metal box containing a  blower, heating or cooling elements  filter racks or chambers, sound attenuators, and  dampers.  Air handlers usually connect to a  ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU. AHU operation is fundamental to the Commercial Building HVAC Control. Increased comfort and operational efficiency may be achieved through advancing the control of an AHU- resulting in more sales, reduced energy costs and satisfied customers.  An air handling unit (AHU) is used to calculate the energy consumption of heating and/or cooling (outside) air to a certain set point. This type is considered to be mainly used in multizone building for ventilation. There are two main types of air handling unit — t

Enthalpy and Entropy

Enthalpy and Entropy Enthalpy Enthalpy is the heat energy content of moist air. It is expressed in Btu per pound of dry air and represents the heat energy due to temperature and moisture in the air. Enthalpy is useful in air heating and cooling applications. The enthalpy scale is located above the saturation, upper boundary of the chart. Lines of constant enthalpy run diagonally downward from left to right across the chart. Lines of constant enthalpy and constant wet-bulb are the same on this chart, but values are read from separate scales. More accurate psychrometric charts use slightly different lines for wet-bulb temperature and enthalpy. Entropy Entropy is the measure of a system's thermal energy per unit temperature that is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system. Entropy is defined as the measurement of degree of randomness or in oth

Comfort Parameters For Human Being

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Comfort Parameters For Human Being Five major human comfort parameters are decided for this research study, which influence the indoor human comfort the most. The five parameters are namely thermal comfort, visual comfort, air quality, acoustic, and lighting. Temperature  humidity   flow  pressure  clean air  co2 % Temperature Sensor  RTD Thermocouple  thermistor RTD RTD (Resistance Temperature Detector) is a sensor whose resistance changes as its temperature changes. The resistance increases as the temperature of the sensor increases. RTD works by using a basic principle; as the temperature of a metal increases, so does the resistance to the flow of electricity. An electrical current is passed through the sensor, the resistance element is used to measure the resistance of the current being passed through it. Thermocouple  Thermocouple are the most common sensor types used to measure temperatures. These are preferred over the others for measurements because they avoid the tedious proce

Dew Point and Saturation Point in BAS

Dew Point and Saturation Point in BAS Dew Point Dew point is the temperature to which air must be cooled to become saturated without changing the pressure.  Changing the pressure affects the vapor pressure and therefore the temperature at which saturation occurs. Thus, the dew point temperature is determined by keeping the pressure fixed. Changes in pressure slightly modify the dew point temperature. The dew point is useful in forecasting minimum temperatures, forecasting the formation of dew and frost, and predicting fog. When the dew point equals the air temperature, the air is saturated and the relative humidity is %100.   The dew point temperature tells us nothing about how many water molecules are in the atmosphere or how close the air is to a relative humidity of 100%. Saturation Point The saturation temperature is the temperature at which the refrigerant changes from a liquid state to a gas. The boiling point is the same as this. The saturation temperature of water at sea level

Security system in BAS

Security system in BAS Security System BAS can control when security systems are engaged and when they’re not. They can manage video surveillance, keyless entries, passcodes and remote access. Benefits of Security System Protection Deterrent to burglars Peace of mind Convenience and energy savings Reduced home insurance premiums Securing the BAS is an ongoing process, and the safety measures need to be followed regularly for its efficient performance. Appoint a team of network administrators to monitor the building management systems regularly. Adopt a holistic approach when installing all the components/systems in the buildings. Identify the vulnerable pockets and monitor them closely. Mark the areas where communication lines are running and monitor the installed physical security systems, such as CCTVs. Ensure that information technology systems have adequate firewalls. Take back-ups of all the data generated and secure it to prevent data theft.

Building Automation System

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Building Automation System A Building Automation System (BAS), (also referred to as a Building Management System or a Building Control System), is a system that controls various electric, electronic and mechanical systems throughout a building. It is a distributed control system that integrates different types of building systems together into one centralized location. Building automation systems are primarily utilized to control the heating, ventilation, and air conditioning (HVAC) in a building, but are also used to control lighting, security and other building systems. BAS works as a computer networking system that monitors and controls a range of other electronic and mechanical systems. It provides a means for these disparate systems to communicate across platforms, software and languages. Building Automation System benefits An extensive BAS can control many systems (such as fire and flood safety, ventilation and security)  at one time, which diminishes the opportunity for human er

Operator Workstation (OWS) in BAS

Operator Workstation (OWS) in BAS The operator workstation are used for monitoring all system operation and for operate control action   The operator workstations are used for monitoring all system operations and for effecting control actions and parameter adjustments. These operator workstations are generally referred to as 'clients' since they obtain their current and historical data from the 'server' computer.

Supervisory Controller in BAS

Supervisory Controller in BAS Supervisory Controller The supervisory controller can be used to access the configuration and status of the programmable controller(s) from a remote computer.  Any device connected to the supervisory controller can access a SCADA interface via a web browser. The supervisory controller module is powered using the local ac power network voltage, obtained from the power source module. 

Direct Digital Control (DDC) in BAS

Direct Digital Control (DDC) in BAS Direct Digital Control (DDC) DDC stands for Direct Digital Control. It is a programmable microprocessor-based system that reads data from BMS input devices, processes that data using programmed logic, and gives output to control equipment in the BMS system. Direct digital control is the automated control of a condition or process by a digital device (computer) Direct digital control takes a centralized network-oriented approach. All instrumentation is gathered by various analog and digital converters which use the network to transport these signals to the central controller Benefits of Direct Digital Control Systems DDC and other building automation systems offer several advantages for building owners, maintenance staff, and facility managers. A well-designed DDC system will Respond quickly to environmental changes, helping maintain more stable temperatures and, ultimately, better occupant comfort year-round Boost energy efficiency through programmab

Field Level in BAS

Field Level in BAS Field Level It is the lowest level of the automation hierarchy and consists of field devices such as sensors and actuators. Sensors, the eyes and ears of automation, collect data on temperature, pressure, speeds, feeds, and so on, convert it to electrical signals, and relay it up to the next level. The main task of these field devices is to transfer data on processes and machines for monitoring and analysis. It also includes the actuators, which are controlled by the next level through electrical or pneumatic signals, converting them into actions. Actuators are similar to the body’s muscles, which are the only way humans can interact with their environments. Actuators turn valves, relays, motors, pumps, and other devices on or off, or adjust their outputs to control the processes. Field level components Sensors These devices track temperature, humidity, the number of people in a room, the lighting level, and other values. The sensors transmit this information to cent

Differentiate between Modbus and LonWorks Protocol

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Differentiate between Modbus and LonWorks Protocol

Differentiate between BACnet and LonWorks Protocol

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Differentiate between BACnet and LonWorks Protocol

Differentiate between BACnet and Modbus Protocol

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Differentiate between BACnet and Modbus Protocol

Communication protocols used in BAS

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Communication protocols used in BAS DeviceNet SOAP XML BACnet LonWorks Modbus  DeviceNet DeviceNet is a network protocol used in the automation industry to interconnect control devices for data exchange. It utilizes the Common Industrial Protocol over a Controller Area Network media layer and defines an application layer to cover a range of device profiles. Typical applications include information exchange, safety devices, and large I/O control networks. DeviceNet was originally developed by American company Allen-Bradley (now owned by Rockwell Automation). It is an application layer protocol on top of the CAN (Controller Area Network) technology, developed by Bosch. DeviceNet incorporates a connection-based network.  SOAP Simple Object Access Protocol (SOAP) is a lightweight XML-based protocol that is used for the exchange of information in decentralized, distributed application environments. You can transmit SOAP messages in any way that the applications require, as long as both the