Fabricating a Heated Copper Chair: Design and Implementation

Introduction

The proposed title of this project is Fabricating, and design of a heated chair made of copper on the sitting region and beneath mainly for holding slippers and towels. The project concentrates mainly on fabricating as well as designing a heated chair made of copper and characterized by sitting area designed of copper material and a designed beneath region for hanging towel and placing of slippers. The design and fabrication of this particular type of chair should work towards fulfilling the project scope, that is, use of chair can apply in wide ranges and in all possible laboratories.  Completion of the project would mean giving close attention and provision of relevant knowledge gained at the study phases for the entire period of learning. The required knowledge will comprise of the analytical skill as well as technical know-how for dealing with mechanical engineering related equipment such as drilling machine, shearing machine, grinding machine, bending machine among others (Kaforey et al.2018).

 

 

 

 

 

 

 

The main objective of the project is to establish a heated chair built of copper and of other material for the sitting area, and also of designed beneath mainly for holding slippers and hanging of towel. The project also aims at implementing a pump as well as plated heat exchanger that will ensure control of the heater chair by means of thermostats. This is to make the chair a heating system such that the motion aspect is achieved through other mechanisms.

The employed fans within the heated copper chair were chosen based on a number of factors including reduced amounts of energy consumption, low levels of noise (at the highest attained velocity of 20 dbA) and the non-vibrational aspect. Under cold environments, the heating device plays the role of heat conduction to the local regions of seat and back of the chair, and at the same time, the lining of reflective plenum reflects back the lost radiant heat of the heating device and surface of the body itself back to the body. It is possible to add stretched fabric covers over the copper materials used in designing back and seat of the heated chair to enhance on tactile texture as well as aesthetic value of the chair. The switch allocated on the heated chair is to regulate cooling and heating operations or at the same time switch off the chair. Regulating the level of power to the desired quantities is done under the influence of a knob (Katzenstein, Maquet GmbH and Co KG, 2016).

Figure 1: Design of the heated copper chair diagrams

Segmented thermal manikin used for measurements points out that, under high cooling incidents, active elements of the personal comfort system chair enhance sensible heat loss of the entire body by around 10 to 30W compared to heat loss of the actual heated chair. Variation in the extraction of body heat is determined by nature of the fabric cover used for the personal comfort system chair. The coefficient of performance for the heated chair (given as: extracted body heat/electric input power) under cooling mode ranges between 3 and 8. Under heating condition, decrease in heat loss by the entire body equivalent to the copper chair is approximately 13W at the highest attainable temperature of 20 W.

Problem Statement

After the extensive consultations and review of relevant documentations, I observed that most of the heated chairs though designed of copper does not incorporate the aspect of thermostats and as well does not exhibit the mobility aspects contributed by other technological issues. Heated chair made of copper has also been observed to be limited in the current markets.

1. Copper-heated chair with a material-designed sitting area, and beneath for hanging towel and placing of slippers can be applied for use in various conditions or places including offices and individual rooms.

 

2. The overall weight likely to be supported by the heated chair is about to be revealed, however according to my expectations, the heated chair will be capable of supporting up to over 120 kg.

 

3. The range for the height of the heated chair is between 430mm and 530mm

 

4. The anticipated range for the working height will be around 450mm and 580mm.

Heated chair made of copper is a common figure within the offices as well as personal rooms. Various companies have been using the common design of heated chair with no thermostats for its mobility. The reason for this is due to the extra cost likely to be incurred in the purchase of heated chair made of copper and with underneath for placing slippers as well as towel. Heated chair is just similar to the common chairs used within offices and special rooms, with height as the only difference, since it has a height which is slightly lower than the ordinary chairs used within places like the laboratory that has slightly raised tables. In some cases, the heated chairs are design to have arm rest and back rest which might not be the case with the ordinary chairs like the ones used in dining halls. The heated chair has additional features including underneath design for placing the slippers and for hanging the towel. This is due to the office operations within which the heated chair is to be used (Sahoo et al.2016).

Problem Statement

In the ancient periods, various industrial factories, offices as well as residential places adopted the use of heated chair constructed of materials other than copper and could not be adjusted. Currently, based on the common knowledge and experience of various designers regarding the benefit of working in a comfort condition, various offices have shifted to the use of heated chair designed of copper in order to obtain effective output.  

Through broadening the comfortable ambient dead-band, PCS facilitates easy saving of energy both for the designed building and buildings that have served for a long period of time enhance resilience of the building to cater for future changes in climatic conditions and perform to intense response necessity at extremely high temperatures. The systems of personal comfort can be installed in a manner that provide help to the systems of air conditioning (AC) in place or, within moderate temperature climates, to facilitate reduced conditioning approaches of energy or to eliminate the unified Air Conditioning (Kowalski 2019).

One of such systems of personal comfort is the heated or cooled (thermo-regulated) chair and has been identified to have the ability of enhancing the level of comfort. Some scholars within their research work studied the aspect of ventilated chair consisting of a pair of fans at the back and on the seat to ensure isothermal forced airflow for reasons of cooling. Making reference to the results obtained from the survey, the scholars drew a conclusion that the ambient temperature offered by the heated chair was 30 ⁰C, which is more acceptable. Other scholars within their research works conducted a test on a heated chair within an office (Lee and Yin  2018). The chair is characterized by a pair of air nozzles designed on the armrests.

The obtained results pointed out that the comfort temperature of the heated chair could be at 27 ⁰C, cooling the user to a single unit on the 7-point scale of thermal sensation. Some scholars conducted a test on a car seat in cool conditions heated by a fabric of encapsulated carbon. The obtained results from the tests indicated that thermal comfort could be attained at ambient temperature lower that 20 ⁰C. Some scientists as well within their research process conducted a test on car seat with a cooled and heated surface under water tubes, regulating further range of the acceptable ambient temperature for the driver to 9.5 ⁰C upwards and 6.4 ⁰C upwards (Cubon et al.2018).

Scope of the project

Some scholars conducted a test on chair with thermo-electric components to provide a heating and cooling mechanism on the seat area. There was an observed improvement in thermal comfort of the chair as well as thermal sensation within temperature ranges between 15 and 30 ⁰C. Though, some users raised complaints on a sensation temperature of 28⁰C resulting from contact developed with the cold surfaces of the seat and backrest of the chair. Another environmental body has come up with another type of heated chair with relatively high energy efficiency. This paper therefore aims at designing as well as determining the appropriate quantity for the heated chair based on comfort performance and also investigate the ambient temperature ranges that ensure desired level of comfort among the users (Venditto and Latta 2020.).

Comfort evaluation for human subjects using the heated chair made of copper material is done under three distinct air temperatures of the room, that is, 30 ⁰C, 18 ⁰C and 15 ⁰C. The chamber was maintained at a relative humidity of 49 + 1% and velocity of air below 0.1 ms^-1. A large number of individuals took part within every test condition for the total number of tests. The selected individuals were of normal body mass index (BMI) and of sample range between 20.0and 25.0 for BMI and of age bracket of 20-30 years. The size sample and subjects’ features can likely be compared to the features of past studies. With the aim of reducing cultural differences, selection is made among the subjects who have spent most of their time, a minimum of three years within the selected region (Javaid, et al.2018).

Four different workstations are to be installed within the functional unit chamber. The dimensions of the chamber are given as 6m by 6m by 3m, windows on either sides, or assuming the actual office surrounding. Shading of the triple-glazed windows is appropriately done by use of fixed external shades. The inner glass pain is designed in a manner that it has a controllable temperature and is maintained at isothermal with internal condition.

The selected subjects should dress in light clothing (light shoes, long pants and t-shirt and clo value of 0.5) during summer seasons. For the winter seasons, the subjects are expected to dress in thick long-sleeve shirt mainly for improving clo value to around 0.8. at the test periods, the subjects were expected the regulate the levels of cooling as well as heating for the heated chair made of copper by use of control knobs on every heated chair. The subjects are also to carry out activities related to computer operations at the testing period, comprising of personal assignments.

Literature Review

Predefined plan for the test

Two Hours Ten Minutes Tests

The recommended temperature for this type of test ranges between 16 and 29 ⁰C. The test is separated into four different phases each lasting for a period of 30 minutes and at break intervals of 5 min. After getting into the test environment, the subjects are requested to have a sit on the heated chair and regulate power to levels of interest. The initial phase is to ensure stability of the subjects. From the four chairs, two are covered with fabric over the copper mesh material. Position of the heated chair is changed at the second break, that is, subjects shift between the covered and the uncovered heated chair.

At the break intervals, the subjects are expected to get off the heated chair and make 10 steps vertically on a step-stool of 22 cm high (Shahzad et al.2018). The vertical movement is to assume the metabolic increase experienced by the subjects on their movement out of the desks within the actual surrounding of the hotel. The last phase is mainly for testing the extra adaptive measures of the climate. In the case of warm tests with temperature of 28 ⁰C, the users are to be supplied with 1.3 W USB-powered desk fan, while for the case of cool tests with temperature values of 15⁰C, the users can put on another layer of sweatshirt as per their interest, mainly to achieve the overall insulation of 1.0 clo.

(Highlighted parts represent the administration periods of the survey; number 1-3 is the total number of employed surveys for statistical analysis while the sections written in italics represents the performance or performed the task of demonstrating the activity carried within every phase)

The test only uses temperature condition of 18⁰C. The test bears some similarities to the initial one other than the last section where the use of fan is implemented, and the subjects are to put on additional clothing. The employed short surveys are to evaluate the total amount of time that the heated chair requires to alter thermal comfort as well as thermal sensation once the subject is out of the workstation (Cicirelli et al.2018).

Thermal sensation and comfort

There has been testing of chair, that has been heated and cooled thermoelectrically versus two conventional office chairs in a similar environment situation. Those two chairs, one which has been meshed and another one cushioned gave out similar responses of thermal comfort to the individuals occupying it. The same way the latest study kept to the similar test conditions as well as study, which was done earlier, the outcomes of the first study was used as a reference conditions for doing test to the new chair. Performance of statistical analysis was done by application of the permutation test through the use of software R. There was comparison of every configuration against others.  Then the big “”” represented below the condition used as the reference in the box. It showed that the differences between the configuration of the reference as well as the configurations of personal comfort systems chair are important statistically. There was presentation of the outcome for the thermal sensations of the whole body as well as the thermal comfort of the whole body for the conditions of the environment as shown below in the two figures:

Figure 2: Figure showing the thermal sensation of the whole body. The ‘cover’ shows the cover made out of fabric over the mesh surcease of the chair. The ‘extra clo’ shows the added layer of the clothing. The ‘chair + fan’ shows the usage of the fan that is placed on the desk.

The figure above showed that the personal comfort system affected the thermal sensation of the whole body by scale units of 1-2 of thermal sensation which was done on the environmental conditions. Even though the cooling and heating of the chair is mainly for the local sections of the whole body, there was occurrence of the strong effect.  At the temperature of 30⁰C using the fan in the desk promotes the impact of the personal comfort system chair, making the thermal sensation to move towards the neutral. At the temperature of 15 ⁰C the combined personal comfort system as well as the extra clothing layer too made the thermal sensation to move towards the neutral (Gdaniec, Draegerwerk and Co KGa 2019).

The chair that has a cover as well the one that lacks cover has no important difference statistically in all the three temperatures. The thin layer of the cover between the body, the seat of the chair as well as the back of the seat cannot degrade thermal sensation for cooling or heating as well (Underwood et al.2018). The variation observed are all in the direction predicted, such that this cover slightly lowers the transfer of the heat for cooling as well as heating.

The addition of the sweatshirt gave out an important variation statistically between the ‘’extra clo’’ as well as the ‘’cover’’ configurations and a p value that is nearing significance of (0.07) between ‘’extra clo’’ as well as ‘’no cover’’ configurations. There is a small effect of the covering of the cloth chair. As shown in the figure above for the thermal comfort of the whole body, it was represented in three different temperatures. The figure showed the percentage of the votes on the comfortable section of the scale below the name for every configuration (Simma, Mammoli  and Bogus 2019). The heated chair made of copper enhanced effectively the thermal comfort of the whole body in all the conditions of testing.

At the temperature of 15⁰ C the heated chair made of copper increased the fraction of those members who preferred that range from a percentage of 20% for the case of the reference to a fraction of 74%. Even though there was registered variation in the general thermal sensation it did not have any effect on the thermal comfort of the whole body. At temperature of 20⁰C the heated chair made of copper improved the thermal comfort which raised the fraction of the comfortable vote from 30% to 90%. Now the outcome of the thermal comfort at the t temperature of 30⁰C is same as the results of the thermal sensation. The individual chair has a strong impact on the thermal comfort as well as the combined heated chair made of copper and the desk fan powered by the USB which were at very high fractions of the members reaching a percentage of 90% (Carmichael et al.2016).

Through cooling conversely, the contact surfaces of the chair with the temperature of the room, the chair will actually be avoiding overcooling on the pelvis and back sections as for the case of the warm environments. The installed fan within the chair has got very significant impact on the movement of air preferably in the warm conditions.

Peculiar questions were raised for the parts of the body that were influenced mostly by the heated chair made of copper, the pelvis as well as the back. Reports are given on the results for the thermal sensation, thermal comfort of the back, thermal sensation of the pelvis area as well as the thermal comfort of the pelvis area. The underneath cover being present on top of the surface of the heated chair made of copper had not important impacts significantly on the thermal sensation as well as the thermal comfort for the pelvis area as well as the back. For the temperature of 30⁰C of the test condition the ‘’chair + fan’’ configuration is not the same statistically in terms of the thermal comfort of the pelvis as well as the back in comparison with the underneath cover configuration. The general thermal comfort that is improved by use of fan seems to have affected the comfort that was perceived for the body parts of the heated chair made of copper although the fan does not cool them directly.

The designed heated copper chair would be capable of providing comfortable conditions as soon as the user sits downs. In the first two minutes, it will be in the cooling mode and later changing to the cooling mode instantly. Each of the individual users would be provided with the capability of adapting in accordance with the personal characteristics thermally.

Thermal sensation as well as thermal comfort of the whole body

The heated chair made of copper has an immense impact on the general thermal sensation of the subjects.  As shown in the figures earlier given, they showed the influential group of the parts of the body that have effects such as the chest, pelvis as well as the back. An expert indicated that sensation that comes from the parts of the body an effect on the general sensation. The heated chair made of copper have effects on the body parts that are influential (Voros and Gentherm 2016). It can show the great influence that was felt by the parts of the body under thermal sensation.

The minimal variance on the outcomes of the thermal sensation as well as the thermal comfort for the heated chair made of copper that has cover and the one that lacks cover. This indicates that the cooling effect that originated from the air that travels into the plenum that is congruent to the human body rather than air moving away from the plenum via the mesh made of fabric. The smooth as well as the thin layer of fabric that is applied in covering the surface of the chair with addition of minimum thermal resistance between the chair plenum as well as the body of the human (Bhimavarapu et al.2018).

At a temperature of 30⁰ C the best outcome was found for the desk fan powered as well as the heated chair made of copper put together.  The variation in the thermal comfort between the chair only as well as the chair plus fan configurations can have relations on the requirement for more air at the level of the head. The expert indicated that cooling the top was vital for relaxation in the hot or warm conditions. Through cooling the faces of the subjects, the desk fan eliminated thermal discomfort that is related to the body part as well as the whole body.

 The numbers below the charts shows the fraction of the subjects who needed more no change or little movement of air. For those two configurations which lacked desk fan, the thermal sensation of the face of the subject suggestions have an average as well as the value of medium for the warm as well as the slightly warm, whereas for the configuration that had the desk fan had values which were almost coming to neutrality (Bhimavarapu et al.2019). There was poor rating of the amount of air movement for the configurations with the heated chair made of copper only, 10% of those that had preference for more air movement. There was increase by the desk fan in the percentage for the subjects that needed no change from 8% to a percentage of 70%.

Consideration of Gender

The study gave room for comparisons of correction of temperature for the men as well as the women in all the conditions of testing. For the individual evaluation of the test condition, the responses of the thermal sensation as well as the thermal comfort for both the males together with the females indicated no variance in any level of the temperatures. Nevertheless, the set of data was small for comparison of the subgroups which had minimum variation.

Through combination of the ‘no cover’ as well as the ‘cover’ conditions they had double sets of data. Through this it adds the difference into the capability of the heated chair made of copper which always has a less cover. It can show a situation in which there is similarity of combination of covered as well as uncovered chairs in a given office.  There was a small variance for the comfort of men as well as women at the temperature of 15 ⁰ C although there is no observable variance in the thermal sensation in any level of temperature.

Conclusion

The designed heated chair made from copper will be expected to provide effective comfortable conditions to a better percentage particularly when the thermostat is regulated between the temperature range of 20⁰C and 30⁰C. As for the remaining percentage of the users, the temperature value will be about 15⁰C. The potential consequences of energy in most of the residential structures are 12⁰C. It is important to note that the saving of energy is never significantly offset by the energy consumption of the chair that is relatively low when compared to the central HVAC. The maximum power of the system of the chair would be 4.5W for the cooling purposes i.e 3.5W is for the chair and 1.0W being for the desk fan. As for the case of heating, the consumption would be 15W. It is important to note further that the design aspect was such that power would only be drawn upon the chair being occupied.