In the general the cooling and dehumidification process is obtained by passing the air over coil through which the cool refrigerant, chilled water or cooled gas is. Thermal design of cooling and dehumidifying coils intechopen. In addition to water, a variety of other heating and cooling media can be used such as glycol and brine solutions and thermal oils. Water cooling coils type kws coils type kws coils are specifically designed and engineered to meet most applications requiring normal water quantities and normal water pressure drop. Ripley spring has finally reached new england and i dont know about you but this winter seemed exceptionally long. Air pressure drop this is the air pressure drop for the coil at standard rating conditions.
Feb 08, 2016 psychrometrics chapter 3 abe 474 indoor environmental control dr. An improved simple chilled water cooling coil model. The simple model provides a good prediction of the air and water outlet conditions without requiring the detailed geometric input required for the detailed model. Thermal characteristics enhancement of helical cooling. Keys to efficient dehumidification page 4 reheat dehumidification via mechanical cooling occurs by driving the conditioned air temperature down to the desired dew point. You need to determine if in fact your pulling in only 10% osa also what is the normal summer osa temp and r. Higher air and water velocities yield higher cooling capacities.
For cooling and dehumidifying coils, mccullagh et al. Coils should be provided with 24 between coil bank and adjacent piece of conditioning equipment. Type kws coils are counterflow, single serpentine circuited to deliver absolute maximum performance. The reheat energy is essentially free, because it is heat rejected from the cooling process and saves on expensive extra energy from outside the process. However, these correlations are inadequate for modelling cooling and dehumidifying coils because beecher and fagans data are restricted to dry fins and to a limited range of coil configurations. Standard ship almost all coils ship in 45 weeks as standard. Comparison of two methods of improving dehumidification in. Cooling the condenser coil with the cool air from the evaporator is ideal since the low air temperature makes the refrigerant condenser very efficient. Mar 22, 2017 hvac cooling load calculation training and learninghap software tutorial english part 4 to 6 duration. Changing the state of air by heating, cooling, mixing. Moist air at atmospheric pressure enters a cooling.
Finned and unfinned coils base case were tested at wide ranges of air flow rates, temperatures and humidity at vertical and horizontal orientations. Standard and custom designs are available for new and retrofit installations. The results showed that i for all coil orientations and operating conditions, the finned coil always has better performance dehumidifying capacity, heat transfer rate, heat transfer coefficient and coil effectiveness compared to the unfinned coils ii placing the coil finned or unfinned coils at vertical orientation enhances the coil. Pdf thermal design of cooling and dehumidifying coils. The water or similar liquid passing through the heat exchanger is single phase, and the humid air is assumed to be moist enough that condensation on the heat exchanger surfaces is possible. Its performance has a strong bearing on the ulti mate indoor environmental conditions, which in turn, has a significant impact on the indoor air quality. The cooling system utilizes a two stages 40 ton 2x 20 ton compressors condensing unit connected with refrigerant piping to two face split cooling coils in an air handling outdoor unit for mixed air preparation.
A simplified dynamic model for chilledwater cooling and. This paper develops a computationally fast, distributed model for the transient behavior of cooling and dehumidifying coils. The leaving air dry bulb temperature should be 6 or more degrees f above the entering water temperature. Changing the state of air by heating, cooling, mixing, humidifying or dehumidifying processes basic air condition processes heating, cooling, mixing, humidifying and dehumidifying by adding steam or water psychometric diagrams and the mollier charts. Existing models in the literature have not been validated fully using experimental data and have not been evaluated in terms of tradeoffs between model accuracy and computational requirements. Facility for testing cooling and dehumidifying coils. Khamis mansour and others published thermal design of cooling and dehumidifying coils find, read and cite all. All of the operations are controlled through a ddc control system. Dxevaporator coils recoil solutions direct expansion dx coils are suitable for use in a wide variety of hvac air cooling and dehumidifying applications. Transient modeling of chilled water cooling coils purdue epubs. The cooling coil is a particular case of the heat exchanger modeling presented in section heat exchangers with and without dehumidification. Direct dehumidification with desiccantbased dehumidifiers.
Cooling and dehumidifying coils are freezing hvacr. Hvac cooling load calculation training and learninghap software tutorial english part 4 to 6 duration. Elattar mechanical engineering department, benha high institute of technology, benha 512, egypt. The air pressure drop is a function of flow rate, fin type, rows and fpi. Direct dehumidification with desiccantbased dehumidifiers humidification is not always required in an hvac system but, when required, it is provided by a humidifier. This engineers newsletter describes several dualtemperature chiller plant configurations that can provide two temperaturesone cool enough to provide sensible cooling but warm. Introduction the cooling and dehumidifying coil is a critical component of air conditioning. Dehumidification basics 101 tech to tech columnapril 08 make daily deposits to your box of knowledge, soon it will have many reference cards. When the room air passes over this coil, it gets cooled and dehumidified. With a wide array of distributors and txvs, we are able to provide proper reduction of pressure and temperature to optimize coil performance.
Dx evaporator coils are designed to be used in airside applications for cooling, heating, and dehumidifying. Applications that require air temperature to be driven down for dehumidification purposes, but do not require the amount of cooling, can be provided with a heatpipe runaround system. Dehumidifying with dedicated outdoor air system configurations a dedicated outdoorair handler separately filters, cools, dehumidifies, heats, and or humidifies all ventilation outdoor air. Hassab mechanical engineering department, faculty of engineering, beirut arab university, lebanon 1. Evaluation of fin efficiency concept in cooling and. Process equipment for heating, cooling and dehumidifying hvac equipment for comfort heating and cooling a wide variety of heat recovery equipment. To prevent the liquid in the tank from leaking into the cooling water, the coil was isolated but kept up to pressure by closing and slipplating the exit water valve but leaving the inlet valve open. The cooling coil in a storage tank developed a small leak. It also can enable the direct control of indoor humidity. Dehumidification with cooling coils only hvacr engineering. A comprehensive experimental investigation of the performance enhancement of cooling dehumidifying helical coils using strips fins was conducted. The cooling and dehumidifying coil is a critical component of air conditioning. The air exiting the system is to have a temperature of 20c and a relative humidity of 50%. Moist air at atmospheric pressure enters a cooling and dehumidifying system at a relative humidity of 80% and a volumetric flow rate of 2.
Gla sales acoils are suitable for use in a wide variety of hvac air cooling and dehumidifying applications. Topics include a discussion about the impact of both water and air velocities on. Air cooling and dehumidifying coils clicking on a companys name will take you to their web site. This standard applies to forcedcirculation air cooling and airheating coils, as defined in section 3 and classified in section 4 of this standard, and for application under nonfrosting conditions. In addition, on dehumidifying coils, the air pressure drop is affected by the condensate on the fin surface. Decisions made to select a cooling coil influence the initial investment as well as the costs of installing. The model uti lizes several steadystate performance indices that simplify. Khamis mansour and others published thermal design of cooling and dehumidifying coils find, read and cite all the research you need on researchgate.
There are some exceptions, based on special materials, but 95% of all coils will ship in 45 weeks with no premium. This standard documents a fundamental means for establishing coil performance by extension of laboratory test data to. Flitalas abstract a test facility has been constructed and a test procedure developed to carry out full and partload performance tests on cooling and dehumidifying coils. These systems consist of coils on either side of the cooling coil and use a refrigerant to economically precool and reheat the air stream. For cooling coils, this clearance is to be measured from the upstream and downstream edge of the coil drain pan. Keys to efficient dehumidification michaels energy. The air circulated in the closed loop duct can be heated and humidified after being cooled and dehumidified by the tested coil.
Understanding the dehumidification performance of air. This standard applies to forcedcirculation aircooling and airheating coils, as defined in section 3 and classified in section 4 of this standard, and for application under nonfrosting conditions. Coils can be located adjacent to filter banks when face areas of the components are equal or within close proximity. Related commercial resources ashrae handbook hvac systems and equipment chapter. Development of a simplified model for cooling and dehumidifying coils. When too much air at the desired dew point temperature is supplied to a space, the air must be reheated to maintain desired conditions. There are very few heat transfer data for corrugatedplate fins in the open literature. Thermal design of cooling and dehumidifying coils 369 fig. Angela green university of illinois at urbanachampaign.
Psychrometrics chapter 3 abe 474 indoor environmental control dr. The average air velocity across the face area is called the coil facefrontal velocity and it is. Surface dehumidification on cooling coils simultaneous with sensible cooling. In the central air conditioning systems the cooling coil is cooled by the refrigerant or the chilled water. Chilledwater cooling and dehumidifying coils with corrugated. The paper describes a steadystate model for chilledwater cooling and dehumidifying coils with corrugatedplate fins. Since many technical columns will focus on air conditioning start up. Trane engineers newsletter live series coil selection and optimization abstract in this enl program, trane engineers will discuss the application, selection, and optimization of both chilledwater and hotwater coils. Aerofin spiral fin water coils are used for heating, cooling and dehumidifying. When selecting cooling coils it is advisable for economy to consider.